CLASSIFICATION OF ENZYMES

NAD⁺ -linked dehydrogenase: Pyruvate dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase, alpha-ketoglutarate dehydrogenase, glutamate dehydrogenase, glyceraldehyde-3-P dehydrogenase, lactate dehy­drogenase, 13-hydroxy acyl CoA dehydrogenase, glycerol 3-P dehydrogenase (cytoplasmic).

NADP⁺ -linked dehydrogenase: Glucose-6-P dehydrogenase, 6-Phosphogluconate dehydrogenase, 3-ketoacyl reductase, Enoyl reductase, gluconate dehydrogenase.

FAD⁺-linked dehydrogenases: Succinate dehydrogenase, fatty acyl CoA dehydrogenase, glycerol-3P dehydro­genase (mitochondrial).

 Ans. ‘D’ Individual enzyme

The classification of the enzyme was described in 1961 by the enzyme commission of the International Union of Biochemistry (IUB). According to this classification, each enzyme code number or ‘EC’ number, consisting of four digits:-

• The first digit indicates the main class; that characterizes the type of reaction they catalyzed.
• The second digit indicates the subclass. This indicates the type of group involved in the reaction.
• The third digit indicates the sub-subclass, which denotes the substrate on which enzyme acts.
• The fourth digit specifies the individual enzyme. It indicates the system serial number and name.

Ans. ‘D’ Transferases

Transferases— Enzymes that catalyze the transfer of moieties such as glycosyl, methyl, or phosphoryl groups.

Some of the enzymes are-

• Aminotransferase or transaminase, e.g. SGOT (AST) and SGPT (ALT)
• Kinases (Hexoki­nase glucokinase, pyruvate kinase, etc)
• Transketolases
• Transaldolases
• Transcarboxylases