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Q1) What are Enzymes?
Ans) Enzymes are biological catalysts that are made by the living
cells
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Catalysts are substances that accelerate chemical reactions
by providing an alternative path with a lower Ea and are very specific
catalyst
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They have a specific range of temperature and pH on
which they work best and there action can be represented by the lock
and key hypothesis by Emil Fischer
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Ans) The important factors that influence the velocity of the enzyme
reaction includes:
1) Concentration of the enzymes: As the conc
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of the substrate (in
constant enzyme conc
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A bell shaped curve is
obtained if plotted
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4) Effect of pH: Each enzyme has an optimum pH at which it
works best
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Some may
even inhibit the enzyme activity by combining with the active
site
6) Effect of activators: Some enzymes require certain inorganic
cations or anions as they work as activators to by various
methods (combining with substrate, formation of ES-metal
complex etc
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Q3) Give the classification of enzymes
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Ans) Enzyme inhibitor is defined as a substance which binds with
the enzyme and brings about the decrease in catalytic activity of the
enzyme
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There are
three broad categories of enzyme inhibition
1) Reversible inhibition
2) Irreversible inhibition
3) Allosteric inhibition

1) Reversible inhibition: The inhibitor bind non-covalently with
the enzyme and is reversed is it is removed
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• Competitive inhibition: The inhibitor resembles the real
substrate in shape and their conc
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Whoever
has a high conc
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Examples are:
- Malonate which is an inhibitor for Succinate
Dehydrogenase
- Succinylcholine which is inhibitor of Acetyl
Cholinesterase
• Non-competitive inhibition: These inhibitors bind to the
enzyme at a site other than the active site
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They have no structural resemblance to
the substrate and mostly attach to sites other than the
active site
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If it can be removed without affecting enzyme activity
than it is reversible but if it affects enzyme activity on
removal than it is irreversible
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These
inhibitors are usually toxic substances that poison the enzyme
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Thus enzyme no longer remains able to bind to its specific
substrate
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When the final product of an enzyme catalyzed
reaction binds to the enzyme allosterically inhibits it, it is called
feedback allosteric inhibition
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Others require non-protein molecules called
cofactors to be bound for activity
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Cofactors can be
either inorganic (e
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, metal ions and iron-sulfur clusters) or
organic compounds (e
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, flavin and heme)
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Reactions involving oxidoreduction, group
transfer, isomerization and covalent bond formation require
coenzymes
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Cosubstrates are coenzymes that are loosely
bound the enzyme
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Prosthetic groups are tightly bound and are nonpolypeptide in a unit that is regenerated in each enzymatic
turnover
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Inorganic examples
include Fe2+, Cu2+, Zn2+ etc
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Coenzymes from B-complex vitamins: Most of the
coenzymes are the derivatives of water soluble complex
vitamins
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Non-vitamin coenzymes: Not all coenzymes are vitamin
derivatives
...
They may be considered as non-vitamin
coenzymes e
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ATP, CDP, and UDP etc
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Such coenzymes
are, therefore, regarded as nucleotides e
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NAD+,
NADP+, FMN, FAD, coenzyme A, UDPG etc
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Write the type of
a) LDH Isoenzymes
b) CPK Isoenzymes
Ans) The multiple forms of an enzyme catalyzing the same reaction
are Isoenzymes or Isozymes
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a) LDH stands for lactate dehydrogenase and catalyzes the
interconversion of lactate and pyruvate
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LDH1
has more positive charge and is fastest in electrophoretic
mobility while LDH5 is the slowest
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M is basic and H is
acidic
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It has three
Isoenzymes
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Isoenzymes

Subunit

Tissue of origin

CPK1

BB

Brain

CPK2

MB

Heart

CPK3

MM

Skeletal muscle



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