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2. Assignment
 Name Amjad Khan
 Submitted to Dear Sir Ghadir Ali
 Subject Bacterial Phasology and
Anatomy
 Topic ENZYMES & CLASSIFICATION OF
ENZYMES
 Date 06/06/2015

3. ENZYMES

4. DEfiNitioN
 Enzymes are protein catalysts for
biochemical reactions in living cells
 They are among the most remarkable
biomolecules known because of their
extraordinary specificity and catalytic
power, which are far greater than those
of man-made catalysts.

5. Naming
The name enzyme (from Greek word "in yeast")
was not used until 1877,
but much earlier it was suspected that
biological catalysts
are involved in the fermentation of sugar
to form alcohol
(hence the earlier name "ferments").

6. NaMiNg aND ClaSSifiCatioN
of ENZYMES
 Many enzymes have been named by adding
the suffix -ase to the name of the substrate,
i.e., the molecule on which the enzyme
exerts catalytic action.
 Forexample, urease catalyzes hydrolysis of
urea to ammonia and CO2, arginase catalyzes
the hydrolysis of arginine to ornithine and
urea, and phosphatase the hydrolysis of
phosphate esters.

7. Classification of enzymes
 Oxido-reductases (oxidation-reduction
reaction).
 Transferases (transfer of functional
groups).
 Hydrolases (hydrolysis reaction).
 Lyases (addition to double bonds).
 Isomerases (izomerization reactions).
 Ligases (formation of bonds with ATP
cleavage).

8. The structure of enzymes
 Protein part + Non- protein part
 Apoenzyme + Cofactor= Holoenzyme
 Function of apoenzyme:
 It is responsible forthe reaction
 Function of cofactor:
 It is responsible forthe bonds formation between
enzyme and substrate
 Transferof functional groups
 Takes plase in the formation of tertiary structure
of protein part

9. Cofactor
 1. Prosthetic group (when cofactor is
very tightly bound to the apoenzyme and
has small size )
 2. Metal ion
 3. Coenzyme(organic molecule derived
from the B vitamin which participate
directly in enzymatic reactions)

10. Prosthetic group
 1. Heme group of cytochromes
 2. Biothin group of acetyl-CoA
carboxylase

11. Metal ions
 Fe - cytochrome oxidase, catalase
 Cu - cytochrome oxidase, catalase
 Zn - alcohol dehydrogenase
 Mg - hexokinase, glucose-6-phosphatase
 K, Mg - pyruvate kinase
 Na, K – ATP-ase

12. Coenzyme
 B1
 TPP- Thiamine Pyro Phosphate
 B2
 FAD- Flavin Adenine Dinucleotide
 FMN- Flavin Mono Nucleotide
 Pantothenic acid
 Coenzyme A (CoA)
 B5
 NAD– Nicotinamide Adenine Dinucleotide
 NADP- Nicotinamide Adenine Dinucleotide
Phosphate

13. Chemical Kinetics

14. The Michaelis-Menten Equation
 In 1913 a general theory of enzyme action and kinetics was developed by
LeonorMichaelis and Maud Menten.

1. Point А.
2. Point В.
3. Point С.

15. Mechanismof enzyme reaction
 1. Formation of enzyme – substrate
complex
 E + S → ES
 2. Conversion of the substrate to the
product
 ES→ EP
 3. Release of the product from the
enzyme
 EP → E+P

16. The Free Energy of
Activation
 Before a chemical reaction can take place,
the reactants must become activated.
 This needs a certain amount of energy
which is termed the energy of activation.
 It is defined as the minimumamount of
energy which is required of a molecule to
take part in a reaction.

17. The Free Energy of
Activation
 For example,decomposition of hydrogen
peroxide without a catalyst has an
energy activation about 18 000. When
the enzyme catalase is added, it is less
than 2000.

18. The Free Energy of
Activation
 The rate of the reaction is proportional to
the energy of activation:
 Greater the energy of activation
 Slower will be the reaction
 While if the energy of activation is less,
 The reaction will be faster

19. Energy of Activation

20. Effect of pHon Enzymatic Activity
 Most enzymes have a characteristic pH
at which their activity is maximal (pH-
optimum);
 above or below this pH the activity
declines. Although the pH-activity
profiles of many enzymes are bell-
shaped, they may be very considerably
in form.

21. Effect of pHon Enzymatic Activity

22. Effect of Temperature on
Enzymatic Reactions
. Therateof enzymecatalysedreaction
generallyincreases withtemperaturerange
inwhichtheenzymeis stable. Therateof
most enzymatic reactions doubles foreach
100
C riseintemperature. This is trueonlyup
toabout 500
C. Abovethis temperature, we
observeheat inactivationof enzymes.
Theoptimumtemperatureof anenzymeis that
temperatureat whichthegreatest amount of
substrateis changedinunit time.

23. Effect of Temperature on
Enzymatic Reactions

24. 1. Reversible inhibition
A. Competitive
B. Non-competitive
C. Uncompetitive
2. Irreversible inhibition

25. CompetitiveInhibition

26. Usage competitive inhibition in
medicine
 The antibacterial effects of
sulfanilamides are also explained by
their close resemblance to para-amino-
benzoic acid which is a part of folic acid,
an essential normal constituent of
bacterial cells. The sulfanilamides inhibit
the formation of folic acid by bacterial
cells and thus the bacterial multiplication
is prevented and they soon die.

27. Non-competitiveInhibition
 In this case, there is no structural
resemblance between the inhibitor and
the substrate. The inhibitor does not
combine with the enzyme at its active
site but combines at some other site.
 E + S +I =ESI (INACTIVE COMPLEX)E + S = ES
ES + I = ESI

28. Uncompetitive inhibition
 E + S +I =ESI (No active complex)

29. Irreversible Inhibition
 The inhibitor is covalently linked to the
enzyme.
 The example:
 Action of nerve gas poisons on
acetylcholinesterase,an enzyme that
has an important role in the transmission
of nerve impulse.

30. Isoenzymes

31. Lactate dehydrogenase
 It occurs in 5 possible forms in the blood
serum:
 LDH1
 LDH2
 LDH3
 LDH4
 LDH5

32. Structure of LDH
 Each contains 4 polypeptide chains
which are of 2 types: A and B which are
usually called M (muscle) and H (heart).
 LDH1 –H H H H
 LDH2 – H H H M
 LDH3 – H H M M
 LDH4 – H M M M
 LDH5 – M M M M

33. Clinical importance of LDH
 Acute myocardial infarction
 LDH1 and LDH2
 Acute liver damage
 LDH4 and LDH5

34. Creatine kinase
 It has 3 isoenzymes:
 CK1
 CK2
 CK3
 Clinical importance:
 When patient have acute myocardial
infarction CK appears in the blood 4 to 8
hours after onset of infarction and reaches
a peak in activity after 24 hours.

35. Enzyme-Activity Units
 The most widely used unit of enzyme
activity is international unit defined as that
amount which causes transfo rm atio n o f 1 . 0
m km o lo f substrate pe r m inute at 25°C
under
 The spe cific activity is the num be r o f
e nzym e units pe r m illig ram o f pro te in.

36. Enzyme-Activity Units
 The m o lar or m o le cular activity, is the
num be r o f substrate m o le cule s
transfo rm e d pe r m inute by a sing le
e nz ym e m o le cule
 The katal(abbreviated kat), defined as
the amount of enzyme that transforms 1
m o l of substrate per 1 sec.

37. THE END
THaNk you
06/06/2015