Classification of co- enzymes

1. Co-Enzymes

2. Co-Enzymes
Enzymes sometimes are conjugated
proteins
Enzyme (conjugated protein)=Apo-enzyme
(inactive)
The non-protein part = Co-enzyme
Apo-enzyme + Co-enzyme=Holoenzyme
(active)

3. Apo-Enzyme and Co-Enzyme
Some enzymes have two parts
The protein part is called
Apoenzyme
The non-protein part is called Co-
enzyme
When tightly bound the Co-enzyme is
called Prosthetic-Group

4. Classification of Co-Enzymes
Coenzymes can be classified by
two ways
( I ) Classification based on
functional characteristics
(II )  Classification based on
structure

5. (I) Classification based on functional
characteristics
A. Transfer of group other than H
1. Sugar Phosphates
2. Thiamine pyro-phosphates
3. Pyridoxal Phosphate
4. Folate co-enzyme
5. Co-enzyme A
6.Biotin
7.Cobamide co-enzyme B12
8.Lipoic Acid

6. B. Transfer of H+
group
1. NAD+
, NADP+
2. FMN , FAD
3 LIPOIC ACID
4.C0-ENZYME Q

7. (II) Classification based on
structure
Presence of Adenine ring
joined to Ribose
Many Co-enzymes may
therefore be regarded as
derivatives of Adenosine
mono phosphate .They are:-

8. Co-enzymes as Adenosine Derivatives
1. Active Methionine
2.Amino Acid Adenylate
3.Active Sulphate
4. 3’ 5’ Cyclic AMP
5. NAD, NADP
6. FAD
7.Co.A

9. Characteristics Of Co-Enzymes
 Co-Enzymes are :-
 Thermo stable
Dialyzable
Non- colloidal
Non-protein
Are altered at the end of a reaction and
sometimes may be changed
They usually belong to the Vitamin ‘B’
complex group

10. Co-Enzyme Vitamin
Derivative
Enzyme
Requiring
TPP
Co-Decarboxylase Vitamin B1
Thiamine
Pyruvate Dehydrogenase
α.Keto Glutarate
Dehydrogenase
Transketolase
FAD
FMN
Vitamin B2
(Riboflavin)
D-amino acid Oxidase
L-amino acid Oxidase
Pyridoxal PO4
Co-Transaminase
Vitamin B6
Pyridoxine Transaminase

11. Co-Enzyme Vitamin
Derivative
Enzyme
Requiring
Co-Enzyme A
Co-Acylase
Vitamin
Pantothenic Acid
Thiokinases
Thiolases
NAD+
NADP+
Vitamin
Nicotinic Acid
LDH,Alcohol
Dehydrogenase
G-6-P Dehydrogenase
Tetra Hydro Folate
(FH4)
Folic acid
One Carbon
Transfers
Thymidilate Synthase
Serine Trans Hydroxy
methylase
Cobamide
Co-enzyme
Vitamin B12
Homocysteine methyl
Transferase

12. Co-Enzyme Vitamin
Derivative
Enzyme
Requiring
Biotin
Co-Carboxylase
Vitamin
Biotin
Acetyl CoA
Carboxylase
Pyru: Carboxylase
Ubiquinone
NADH
Dehydrogenase
Cytochrome b
Heme
Co-enzyme
- Peroxidase
Catalase
Cytochrome

13. Function of Co-enzymes
They accept atom or group from a
substrate and transfer it to the other
molecule.
Eg: Transaminases
R─NH2 + R1─ C ═ O + PyPO4
PyPO4─NH2
R1─ NH2 + R─ C═ O + PyPO4

14. NAD and NADP act as hydrogen
acceptors in dehydrogenating
reactions
T.P.P functions in oxidative
decarboxylations.
CoA in Acyl group carrier
Tetrahydrofolate as formate
carrier in the synthesis of Purines
and Pyrimidines.

15. PROENZYMES
Some enzymes, particularly
the Proteolytic enzyme ,
may be secreted as inactive
proenzymes or zymogen.

16.  At the active site ,one or more specific
covalent peptide bonds of each such pro-
enzymes are hydrolyzed either
enzymatically or by pH changes to yield
the active enzyme and some inactive
peptides called masking substances
Hydrolysis makes the active site of the
enzyme free and available to catalytic
action.

17. PROENZYME ACTIVATOR PRODUCTS
Pro-
Enzyme
Activator Active
Enzyme
Masking
Substances
Pepsinogen
HCl
or Pepsin
Pepsin Inactive
peptide
Trypsinoge
n
Enterokina
se
Trypsin Inactive
Hexapeptide
Chymotryps
inogen
Trypsin,Ch
ymotrypsin
α-
Chymotrpsin
α-Inactive
Peptide

18. PROENZYME ACTIVATOR PRODUCTS
Pro-Enzyme Activator Active
Enzyme
Masking
Substances
Pro-
Carboxypept
idase A
Trypsin Carboxype
ptidase A
Inactive
Peptide
Prothrombin Prothromb
inase
Thrombin Inactive
polypeptide
Pro-
Fibrinolysine
Fibrino
lyso
Kinase
Fibrino
Lysine
Inactive
Peptide