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This is updated on 22nd Nov, 2009 and going to be updated frequently
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41) Complexes of which of the following metals are used in the treatment of rheumatoid arthritis:
1
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Ruthenium
3
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Copper
Explanation
* Gold salts (containing Au(I)) like Auranofin, Sodium aurothiomalate, aurothioglucose are
used to treat rheumatoid arthritis
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* Iron in the form of ferrous sulfate, ferrous gluconate are used in treatment of iron deficiency
anemia
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* Sb(III) salts are used in eczema (inflammatory condition of skin)
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* BaSO4 is used as contrast agent in radiography
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* 99mTc (in Cardiolyte) is used in radio diagnostics
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It’s half life is 6hrs only and emits gamma rays
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* Selenium sulfide used to treat seborrheic dermatitis and Tinea versicolor
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It is also used as an antitumor agent
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are used for biocatalysis
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Helps in active and passive transport
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2+
* Mg : Present in chlorophyll
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Information carrier;
Present in endo and exo skeletons
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In muscle and nerve functions - cell signalling
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tinel at synapse
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IV/V
* V , MoIV/VI, WIV/VI, MnII/III/IV, FeII/III, NiI/II/III, CuI/II: electron transfer
* Fe and Cu: Transport and storage of dioxygen
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* Co:
Cobalamine, e
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Vitamin-B12
* Mn:
In photosynthesis, generation of dioxygen by splitting water
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* Mo, Fe & V: Conversion of N2 to ammonia (nitrogen fixation)
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* Si(IV) Bones
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* Se(II): Selenocysteine
* F-:
As fluorapatite (Ca5(PO4)3F) in teeth
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2+
* Ni :
Hydrogenase and hydrolases (urease)
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Fe : ferritin (related is “transferrin” which transport iron)
Zn : metallothionein
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* Photosynthesis

Mg: chlorophyll in PSI
Mn: part of OEC in PSII

* Hydrolase

Zn: carboxypeptidase
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* Oxidoreductase

Fe: oxygenase, hydrogenase
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HT

* Metal storage compound

* Isomerase

Fe: aconitase
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% of Elements in Earth Crust and in Human Body

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Earth crust
Element
%
O
47
Si
28
Al
7
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5
Ca
3
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5
K
2
...
2

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Human body
Element
%
O
63
C
25
...
5
N
1
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31
P
0
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08
S
0
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More stuff - with brief explanation
* Superoxide dismutase, present in the cytosol, is a Cu-Zn containing enzyme catalyzing the
disproportionation of O2- (superoxide) to O22- (peroxide) and H2O
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* In terms of abundance in the human body, zinc is the most important trace element after iron
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ii) zinc finger proteins which recognize specific DNA sequences and are involved in gene
function
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* Normal nitrogenase enzymes contain Mo and Fe, but less common forms with vanadium are
also known
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* Vitamin B-12 contains Co(III)
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(Can you mention the
difference between heme and corrin ring systems?)
* Among the metals present in human body, the most abundant is Calcium
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These elements have strong complexing ability and
an especially strong affinity for sulfur
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Once attached to suitable ligands
they are hard to displace
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It uses chelating ligands
like EDTA that bind very strongly with toxic elements in complexed form and remove them
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1) Give the structure, hybridization and magnetic moment of cis-platin? Write its action
on cancer cells
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* Pt (Z=78)
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with e
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* Hybridization of Pt2+ is dsp2
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The crystal field splitting of square planar complexes is shown below
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Action: Upon administration to the cancer patient, the chloride ligands are displaced by water
and thus aqua platinum complexes are formed in cells, which bind and cause crosslinking of
DNA---- ultimately triggers apoptosis - programmed cell death
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2) Why are d-metals such as Mn, Fe, Co, and Cu are present in redox enzymes in preference to Zn, Ga, and Ca?
Ans:- Mn, Fe, Co, Cu occur naturally in redox enzymes because they can have at least two stable
oxidation states
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The other metals i
...
, Zn, Ga, Ca, have only one stable oxidation state, and hence cannot be
oxidized or reduced at physiological potentials
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41
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It has the shape of a
hollow sphere
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It is incorporated in the mineral ferrihydrite, [FeO(OH)]8[FeO(H2PO4)], which is attached to the inner
wall of the sphere
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Ferritin that is not combined with iron is called apoferritin
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Affinity to iron decreases with decrease in pH
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HT

41
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It helps in generation of dioxygen by oxidising water molecule
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These help in electron tranfer reactions
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5) What is the active site in carboxy peptidase? Mention its role?
Ans:- The active site in carboxy peptidase contains tetrahedrally coordinated Zn2+
...

OH2
2+

Zn
His(N)

O(Glu)

His(N)

TP V
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A VA
DI R
CH D
EM HA
AD N
I
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It removes C-terminal aminoacid from a protein
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Thus this enzyme helps
in degradation of peptides in biological systems
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Do you know the Edman degradation (in the laboratory) is a method for removing the N terminal amino acid? If you don’t, just remember
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6) What is the active site in carboxy anhydrase? Mention its role?
Ans:- The active site in carboxy anhydrase (carbonic anhydrase) contains tetrahedrally coordinated Zn2+
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OH 2
Zn

His(N)

2+

(N)His

His(N)

Function: It catalyzes the conversion of carbondioxide to bicarbonate
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This is crucial step
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Step 2: Thus formed zinc bound hydroxyl group carries out nucleophilic attack on CO2 to
get (His)3Zn-OCO2H complex
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H+

+

2+

(His)3Zn -OH

HT

(His)3Zn -OH2

-HCO 3

H2O

-

CO2

+

(His)3Zn -OCO2H

41
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It is coordinated to two cysteine residues, one histidine residue and one water
molecule
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OH
R

H

R

1

+

NAD

+

O

LADH
R

R

1

+

NADH

+

+

H

TP V
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A VA
DI R
CH D
EM HA
AD N
I
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7) Studies of Zn(II)-containing proteins often make use of Co(II)-for-Zn(II) substitution
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b) Tetrahedral Co2+ and Zn2+ are both diamagnetic
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d) The visible spectra of complexes of Co2+ are similar to those of related complexes of Zn2+
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* The spectral behaviour of Co2+ (d7, paramagnetic) is different from Zn2+ (d10, diamagnetic,
colorless, no visible spectra)
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41
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(b) Zn (II) does not have chemically accessible redox states
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Ans:- The unique features of zinc are
* It exists only in +2 state
...
e
...

* There are no ligand field stabilization effects due to its d10 configuration
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Its geometry and coordination number are only
dictated by ligands and the charge
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* It is a good lewis acid next to copper
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41
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816 mV at pH = 7 and hence is a good oxidizing
agent
...
Explain
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Hence dioxygen is kinetically inert towards organics
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(That is why iron in hemoglobin is to be
protected in the hydrophobic environment of globin
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9) What is Calmodulin (CaM)? Mention its role?
Ans:- Calmodulin (CALcium MODULated proteIN) is a calcium binding protein present in all
eukaryotic cells
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TP V
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A VA
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CH D
EM HA
AD N
I
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10) What are porphyrins? Draw the structures of different types of porphyrins in biological systems
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The simplest porphin found in Hemoglobin is called porphyrin
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In vitamin B12, the two of the pyrrole rings are directly connected to each other
...

Porphyrin is a highly conjugated system and deeply colored
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...
g
...
g
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g
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41
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Ans:- An ionophore is a lipid soluble macrocyclic molecule, which transport ions (especially hard
cations) across the lipid bilayer of the cell membrane
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HT

There are two types of ionophores as follows;
* Carrier ionophores which bind to a particular ion and facilitates its transport through the
lipid membrane
...

* Channel forming ionophores, which form a hydrophilic pore (or channel) in a membrane,
allowing ions to pass through it
...
They usually coordinate through O and N
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Selectivity depends on number of
coordination bonds and confirmation of ionophore
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Ionophores disrupt transmembrane ion concentration gradients, required for the proper
functioning and survival of microorganisms, and thus have antibiotic properties
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Valinomycin (K+)
Salinomycin (K+)
Gramicidin A (H+, Na+, K+) ---- It is a transmembrane channel forming ionophore
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TP V
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12) Why Gadolinium salts are used as MRI agents?
* A good MRI agent should have following charactersitics:
1) High magnetic moment;
2) Long electron-spin relaxation time;
3)
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Practice questions
1) Identify one significant role in biological processes for the elements Fe, Mo, Mn and Cu
...
The
reaction of CO2 with this enzyme is an example of
(a) electrophilic addition
(b) electron transfer
(c) nucleophilic addition
(d) electrophilic substitution
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13) The copper containing non heme respiratory protein is
1) Cytochrome-c
2) Hemerythrin
3) Hemocyanin

4) Myoglobin

TP V
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EM HA
AD N
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17) The ionophore used in the cattle feed to improve the permeability of Na+ and H+ ions is
1) Crown ethers
2) Monesin
3) Ionomycin
4) Nonactin
18) Match the following
A) Silver sulfadiazine
B) Selenium sulfide
C) tetrathiomolybdate
D) Cardiolyte

1) Anti copper agent
2) Skin fungal infections
3) Radiodiagnosis
4) Seborrheic dermatitis

19) The function of Na+ and K+ in biological systems is
1) To maintain osmotic balance in the cells
2) Help in active & passive transport
3) As charge carriers
4) All
20) Fluoride is present in the teeth in the form of
1) CaF2
2) Na3AlF6
3) Ca5(PO4)3F

4) CaF2
...

25) The ionophore valinomycin is highly selective for:
a) K+
b) Na+
c) Mg2+

d) Ca2+

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Hint: The stability constant of complex formed by valinomycin with K+ is 106, whereas that
with Na+ is 10
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Electron transfer
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Proton transfer
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Both electron and proton transfer
4
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TP V
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A VA
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CH D
EM HA
AD N
I
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E
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, Ferredoxins, as well as NADH dehydrogenase, hydrogenases, nitrogenase etc
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* Additionally some Fe-S proteins regulate gene expression
...

In most iron-sulfur proteins, the clusters function as electron-transfer groups
...
These biological "capacitors" can accept or discharge electrons, the effect being change
in the oxidation states (+2 or +3) of the iron atoms
...

The following diagram illustrates the redox scheme between low-potential and high-potential (HiPIP) ferredoxins containing Fe4S4clusters
...
The oxidation numbers of
the iron ions in high-potential ferredoxins can be [3Fe3+, 1Fe2+] or [2Fe3+, 2Fe2+]
S

S

Fe

S

+e-

S

Fe

Fe

+e-

S

S

Fe

S

S

3-

S

S Fe

-e-

Fe

S

S

Fe

S

2-

S

S Fe

-e-

S

Fe

S

1-

S

S Fe
S

S

Fe

S

S

Fe

S

Following is Fe2S2 type of ferredoxin
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* Aconitase hydratase contains Fe4S4 cluster in active form and Fe3S4 cluster in inactive form
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It is also an electron transport agent
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Hemoglobin and Myoglobin
* Hemoglobin(Hb) and myoglobin(Mb) are the heme containing metalloproteins (Note: iron
porphyrin system is called heme)
...
Hemoglobin is present in
RBC and helps in transport of dioxygen from lungs to tissues
...

* Hb contains four heme units and four globular protein sub-units whereas Mb contains only
one heme unit surrounded by a globular protein
...
It enhances the selectivity for O2 binding
...

* In deoxy-hemoglobin, four of the coordinated sites of iron are occupied by nitrogens of
porphyrin ring
...
The sixth position is occupied by weakly bonded water molecule
...

Another histidine group (distal), on the opposite side of the first histidine group, is situated near the iron and assists the binding of dioxygen in ‘end on bent’ confirmation (This
particular bent confirmation discourages the binding of CO to heme iron
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CO binds to hemoglobin 200X
stronger than dioxygen but binds 20,000X stronger with unprotected heme)
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O OC-H2 C-H2 C
N
H

proximal
histidine

* Hb coordinated to dioxygen is called oxy-hemoglobin
...
In oxy-hemoglobin the sixth coordinated position of iron is occupied by dioxygen
in ‘end on bent’ geometry
...
Fe(II) is in high spin state and is paramagnetic
...
78 Ao) and situated above the plane of the porphyring ring
...
It is smaller in size (0
...
Now Fe(II) can move
into the cavity of porphyrin ring and drags the proximal histidine which inturn triggers the
confirmational changes in other globin subunits and opening of other heme sites
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N

N

N
H

N
H

H-bond

CH3

O

H3C

N

H3C

-

O OC-H 2 C-H 2 C

N

N

II

Fe

N

H3C

CH3

CH 2 -CH 2 -COO

-

-

H3C

N

FeIII

N

O

CH3

N

N

O OC-H 2 C-H 2 C

N

CH3

CH 2 -CH 2 -COO

-

HT

N

N
H

Desoxy Hb
Domed porphyrin
High spin Fe(II) - out of ring

N
H

Oxy Hb
Planar porphyrin
Fe(III) - still high spin - into the ring
Bent peroxy oxygen

* There are two theories to explain the nature of Fe in oxy-Hb or oxy-Mb
...
Both are diamagnetic
...
Both are
paramagnetic
...
The O-O

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TP V
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A VA
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CH D
EM HA
AD N
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This is more accurate and modern explanation
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It binds at the centre of
cavity between two beta-Hb units and stabilizes the T-state
...
This won’t affect the affinity
of Hb with oxygen in lungs where the pO2 is very high but decreases the affinity in tissues and
helps in release of dioxygen by stabilising the T-state of Hb
...
Hence oxygen is released more efficiently in the tissues where CO2 concentration is
high
...

* The percent saturation with O2 curve of Hb against pO2 is sigmoidal whereas that of Mb is
hyperbolic
...

* Deoxyhemoglobin is the form of hemoglobin without the bound oxygen
...
This difference is used for measurement of the amount of oxygen in patient's blood by pulse oximeter
...
Most of them contain iron (either in Fe(II) or
Fe(III) oxidation states) at their active site
...

* Cytochromes are classified based on heme type or heme iron coordination
...
The four coordination sites are occupied by
four nitrogens on pyrrole rings of heme group and remaining are occupied by usually Histidine, Cysteine residues
...

The potentials are such that the electron flow is always from
cyt-b ----> cyt-c ----> cyt-a ----> O2
* In the mitochondrial electron-transfer chain, cytochrome-c accepts an electron from cytochrome-c1 and then transfersit to cytochrome c oxidase
...
The CN- ion can bind strongly
to the sixth coordination site and stabilize Fe(III) in cytochrome-a
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CYTOCHROME-C OXIDASE
* Cytochrome-c oxidase (not cytochrome-c) is the major respiratory protein of animal and
plant mitochondria
...
It contains two hemes (with two Fe3+) and
three copper atoms, arranged in three centers
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CYTOCHROME P450
* Cytochrome P450 oxidases constitute a super family of monooxygenase cytochromes
...

* These enzymes are primarily involved in steroidogenesis and detoxification
...

* Their reaction with dioxygen involve higher oxidation states of iron, such as Fe(IV)
...

P450
E
...
1) R 3CH + O2 + 2e- + 2H+  R 3C-OH + H2O


2)

P450

O

H

H
Camphor

O

OH
H
5-Exo-hydroxy camphor

HT

Mechanism:
* The active site has Fe centre which is switched between II, III and IV oxidation states
...

* The substrate RH is bonded by hydrophobic interaction into the protein pocket close to the
active centre
...
Another is converted into
water
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step-1

O

step-2

N

Fe

Fe
N

N

N

N

N

S(Cys)

S(Cys)

S(Cys)

low spin

high spin

O2

-ROH

step-3

TP V
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A VA
DI R
CH D
EM HA
AD N
I
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1) Give the structure of active site in Rubredoxin and mention its role?
Ans:- Rubredoxin is a low molecular weight iron containing bacterial protein involved in electron
transfer
...
However, in contrast to
iron-sulfur proteins, rubredoxins do not contain inorganic sulfide
...

Cys
S

Fe

Cys

S

S

Cys

Active site of Rubredoxin

S

Cys

HT

Rubredoxins perform one-electron transfer processes
...
In both oxidation states, the metal remains high spin,
which helps to minimize structural changes
...

42
...
439V at pH = 7
...
Will Fd
generate hydrogen gas from hydronium ions dissolved in water if the standard potential

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for the reduction 2H+ + 2e- ---------> H2 is -0
...
0
...

Ans:- L:
2H+(aq) + 2e- -----------> H2(g)
; Eo = -0
...
439V

TP V
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A VA
DI R
CH D
EM HA
AD N
I
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439 - (-0
...
86V
------- which is > 0
This means that  rG < 0 (why? see the note)
...
Therefore H2 gas is consumed, and not produced in this
reaction
...
Left hand side half
cell is considered as anode and oxidation occurs in this cell
...

2)  G = -nFE
42
...
State whether
the following reaction is true or false?
nitrite reductase
NO 2 - + ferredoxin-1  NH 3 + ferredoxin-2


Ans:- False
...
Hence only reduced form of ferredoxin can reduce NO2to ammonia as follows
...
4) What prevents synthetic (simple) iron porphyrins from functioning as O2 carriers?
Ans:- In the naturally occuring porphyrins, like Hemoglobin, there is a globular protein around
the heme groups
...
It stops the formation
of Fe-O2-Fe dimer
...
As a result, Fe(II) is oxidized to
Fe(III) and Fe-porphyrins easily dimerize to Fe-O2-Fe and then Fe-O-Fe (a  -oxo dimer) and
hence cannot function as oxygen carriers
...
5) What is the active site in Rieske protein? Identify its role in bilological processes
...

2) the cytochrome b6f complex (found in photosynthetic systems)
...
It was first discovered and isolated by John S
...


The active centre is Fe2S2 cluster in which one iron is coordinated by two cysteine residues
and the other iron is coordinated by two histidine residues
...
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In mitochondria it accepts electron from Ubiquinol and transfers electron to heme iron in
cytochrome-c
...


TP V
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A VA
DI R
CH D
EM HA
AD N
I
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6) Cytochrome C is a redox protein but myoglobin is an oxygen storage protein
...

Ans:- In cytochrome C, the iron the six coordination sites are permanently occupied
...
Hence it cannot store or
carry dioxygen
...

(S)Cys

N

N

Fe

N

N

(N)His

Coordination pattern in Cytochrome C

But in Myoglobin or in Hemoglobin, the sixth coordinated site is occupied by losely bound
water which can be replaced by dioxygen easily
...
(sometimes the iron in deoxy hemoglobin is said to be
pentacoordinated only i
...
, sixth coordinated site is vacant)
O

OH2

O

N

N

N

Fe

Fe

N

N

(N)His

N

N

N

(N)His

Coordination pattern in Mb and Hb

42
...
Explain
...


HT

42
...
Under highly oxidising conditions, iron is oxidized to Fe3+ and forms
insoluble Fe(OH)3
...
But microbes release siderophores to
absorb them
...
Citrate is a simple siderophore
...
g
...
,
Siderophores can fully satisfy the octahedral geometry requirements of iron without
significant distortion and can bind flexibly
...
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2) In humans, iron is mobilized by transferrin
...
8) What is the "Cooperative effect" in hemoglobin?
Ans:- Coordination of one O2 leads to conformational changes in the protein chain leading to facilitated coordination of O2 by the other 3 sub-units in hemoglobin
...

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42
...
Compare the infrared frequency of CO in this complex to that
of free CO
...
This is much less important for Fe(III)-CO because of higher
positive charge on the metal
...
(cf
...
10) Why are all the oxygen carriers that contain iron and porphyrins are found inside the
cells?
Ans:- The inside cell environment is reducing and sustains Fe(II), whereas outside the cell the O2
concentration is high and hence the probability of the oxidation of Fe(II) ions to Fe(III) increases
...
11) Write the steps involved in the formation of hematin, a  -oxo dimer, from free heme
...
The steps involved are summarized below
...

Magnetic susceptibility = 1
...
0 Bohr magnetons, indicating one unpaired electron
...
(Actually the
value should be more)
Asymmetric Fe-O stretching frequency at 730 - 880 cm-1

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42
...
It is a respiratory protein
...
(hemerythrin contains 8 subunits)
Deoxy forms are colorless, whereas oxy forms are violet pink in color
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C
O
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Active site: The oxygen binding site is a binuclear iron centre
...

One iron is hexacoordinate and another is pentacoordinate
...
Then
the hydrogen on hydroxy group is transferred onto peroxide group
...
In this process, an oxo bridge is formed between iron ions
...
Its
affinity towards CO is less than with O2
...
12) What is the active site in Hemocyanin? Mention its role?
Ans:- Hemocyanin is respiratory protein containing two copper centres at the active site
...
It
contains NO HEME
...


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In the deoxy form, each Cu(I) is coordinated to three histidine residues
...

Histidine

Histidine

N

N
N

+

N

Cu
N

Histidine

N

Histidine
N

O
N

2+

2+

N

N

Histidine
N

N

Cu

Cu

O

N

N
Histidine

N

TP V
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A VA
DI R
CH D
EM HA
AD N
I
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The unpaired electrons in both Cu(II) ions couple by a bonding
interaction through the bridging peroxy ligand
...

Spectroscopic evidences of above oxyHemocyanin (oxyHc) structure;
1) Raman spectroscopy indicates symmetric binding and rules out mononuclear peroxo
compound
...

42
...
They are
broadly divided into three types as follows:
Type I :
* Contain single copper atom, coordinated in distorted trigonal planar geometry to two
histidine and a cysteine residue
...

* These are called blue copper proteins or cupredoxins
...
Charge transfer occurs
between Cys-S to Cu(II)
...
LMCT are Laporte permitted and hence
show intense absorption
...

* They have relatively high reduction potentials (> 250 mV)
* Function as electron transfer agent
...
g
...
Coordination through O or N
...

* His, Tyr and H2O are the ligands
...

* There are non blue copper proteins
...
As they are
Laporte forbidden, the color is not intense
...

* Catalyse redox reactions
...
g
...
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* Intense blue color in oxidised form due to LMCT from O2- to Cu(II)
...
The spins are paired up due to covalent overlapping of metal ions through the
bridging ligand
...
g
...


TP V
...
A VA
DI R
CH D
EM HA
AD N
I
...

It is involved in the process of oxidizing Fe(II) to Fe(III) during the transfer of iron from
transferritin to ferrritin
...
g
...

Cuz centre found in nitrous-oxide reductase
...

41
...
Indicate the site on which nitrogen first binds
...

N 2 + 8e- + 8H + +16MgATP  NH 3 + H 2  16MgADP + Pi


All the nitrogenases consists of two subunits
i) M-cluster (FeMo cofactor) - containing Fe, S and Mo
ii) P-cluster
- containing Fe and S
According to modern view, the M-cluster is involved in the reduction of dinitrogen to
ammonia
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(Note: These irons are just having three bonds and with open configuration)
S

S

(Cys)S

Fe

Fe

S

S

Fe

Fe

S

Fe

Fe

S

Mo O

S

Fe

O

S

O

N(His)

HT

S

M-cluster

The P-cluster contains cubane like [4Fe,4S] ferredoxins which are involved in the transfer
of electrons to M-cluster
...

41
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These species
can be eliminated by super oxide dismutases (SODs) and catalases
...
Aditya vardhan

adichemadi(at)gmail
...
Catalases then convert
hydrogen peroxide to oxygen and water
...
The Cu and Zn atoms are connected through
an imidazole ring(of histidine)
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:// AD
W IT
W Y
W A

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C
O
M

His
His

His

During catalysis, the Cu binds to superoxide and cycles between the +1 and +2 oxidation
states
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SOD-Cu

2+
+

+ O2

-

+

SOD-Cu + 2H + O2

+

SOD-Cu + O2

-

SOD-Cu

2+

+ H2O 2

Practice questions
1) What is the role of globular protein in oxygen transport? cf
...
4)

2) Which of the following is correct concerning the differences between hemoglobin and
myoglobin?
A) Hemoglobin is a monomeric protein and myoglobin is a tetrameric protein
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C) Hemoglobin exhibits cooperative binding of O2 while myoglobin does not
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3) The metal present in carbonic anhydrase is
(a) Cobalt
(b) Nickel

(c) Zinc

(d) Magnesium
...

(B) Iron is 5-coordinated
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(D) The oxidation state of iron is +2
...
Aditya vardhan

adichemadi(at)gmail
...

(b) A metal bound superoxide is formed and  O2 decreases
...

:// AD
W IT
W Y
W A

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C
O
M

II
1) Cu at the active site
2) Fe and Cu at the active site
3) Zn at the active site
4) Fe at the active site
5) Mo at the active site
6) Cu and Zn at the active site

(a) P-6, Q-2 R-1, S-4
(c) P-3, Q-2, R-4, S-5

(b) P- 3, Q-2, R-1, S-4
(d) P-5, Q -6, R-1,S-2

8) Match the following
I
P) Cytochrome C
Q) Calmodulin
R) Chlorophyll
S) Alcohol dehydrogenase
(a) P - I
(b) P - II
(c) P - III
(d) P-V

Q - II
Q - III
Q- IV
Q- IV

II

I) Zinc
II) Potassium
III) Magnesium
IV) Calcium

R -III
R -IV
R-I
R - III

S - IV
S-I
S- II
S-I

9) Which statement is the correct description of hemerythrin?
1) A heme protein with one Fe centre at the active site
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3) A non-heme protein with one Fe centre at the active site
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HT

10) Match the following:
P
...
Vitamin B12
R
...
Valinomycin

I
...
Ionophore
III
...
nitrogen fixation
V
...
Iron storage
...
In the

Prepared by V
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WARANGAL

native form there is a methyl or methylene group attached to Cobalt
...
Hence the name cyanocobalamine
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12) The Cu-siderophore used in absorption of Cu by bacteria is
1) Methanobactin
2) Enterobactin
3) Mycobactin

4) Desferrioxamine

13) Inactive form of Aconitase hydratase, which catalyzes the stereospecific isomerization of
citrate to isocitrate via cis-aconitase, contains
1) Fe4S4 cluster
2) Fe2S2 cluster
3) Fe3S4 cluster
4) Fe(S-Cys)4 cluster

TP V
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A VA
DI R
CH D
EM HA
AD N
I
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b) Ceruloplasmin contains all Types of copper centres
...

d) Plastocyanin contains a Type 1 Cu centre
...

f) Hemocyanin contains Type 2 Cu centre
...

2) Cytochrome P-450 couples to cytochrome-c in the mitochondrial electron-transfer
chain
...

4) Cytochrome P-450 contains high-spin Fe(III); this directly binds O2 and acts as an O2
carrier
...

2) A [2Fe–2S] ferredoxin contains six S donors, two of which are S2– ligands
...

4) In a [4Fe–4S] ferredoxin, four redox couples that make use of the four Fe centres are
accessible in Nature
...

The incorrect statement is the 4th one
...

B) an FeMo-protein in which the active site consists of a single [3FeMo-4S] cluster
...
Aditya vardhan

25

adichemadi(at)gmail
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D) an Fe-only containing protein in which the P-cluster is the active site
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21) The enzyme which contains cubane like ferredoxin is
1) Carbonic anhydrase
2) Urease
3) Zymase

4) Nitrogenase

TP V
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A VA
DI R
CH D
EM HA
AD N
I
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b) The affinity of Hemoglobin with CO will be even more without the presence of distal
histidine residue
...
78 Ao)
...
61 Ao)
e) The porphyrin ring in T-state of hemoglobin is dome shaped
...
As a consequence:
1) Affinity of hemoglobin with dioxygen improves in lungs
...

3) More dioxygen is released in the tissues where the pO2 is less
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24) The type of cytochrome with lower reduction potential is
1) Cytochrome a
2) Cytochrome b
3) Cytochrome b
4) All with same reduction potentials

25) In cytochrome-c oxidase, the number of iron centres is _____ and the numbe of copper
centres is ______
...

a) EPR sigal is abnormal in Type-II copper proteins
...

c) Hemocyanin is a Type-II copper protein
...

30) Type I and III copper proteins are intense blue in color due to
a) LMCT
b) d-d transitions
c) MLCT

d) f-f transitions

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WARANGAL

31) EPR signal is absent for which of the following blue copper protein:
a) Superoxide dismutase
b) Hemocyanin
c) Plastocyanin
d) Nitrite reductase
32) The number of MgATP’s required in the reduction of N2 to ammonia is
a) 4
b) 12
c) 16
d) 6
33) The blue copper protein which helps in the transport of iron is
a) Ceruloplasmin
b) Plastocyanin
c) Tyrosinase

d) Nitritereductase

TP V
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A VA
DI R
CH D
EM HA
AD N
I

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