Based on their chemical composition, the enzymes have been classified into three categories:
Few enzymes have been named based on the name of the substance synthesised. Example: Rhodoase.
The name of some enzymes gives due to both the substrate utilised and the type reaction catalysed. Example: Succinate dehydrogenase (catalyses the dehydrogenation of the substrate succinic acid).
The enzymes are highly specific as to the reaction they catalyse. Example: Hydrolase (hydrolysis); isomerase (isomerisation); dehydrogenase (dehydrogenation).
The substrate upon which an enzyme acts is called the substrate. Dudaux (1883) named the enzymes by adding the suffix, ase. Example: Enzymes acting upon carbohydrates are carbohydrase, proteins – protease, lipids – lipase. These are known as trivial names of enzymes.
The International Union of Biochemistry (IUB) appointed an enzyme commission in 1961. This committee made a thorough study of the existing enzyme and devised some basic principles for the classification and nomenclature of enzyme.
A particular coenzyme may participate in catalytic reaction along with different enzymes. Example: NAD+ acts as coenzymes for lactate dehydrogenase and alcohol dehydrogenase. The specificity of the enzyme is mostly dependent on the apoenzyme and not the coenzyme. Table 6.13 Coenzymes Not Related to B-complex Vitamins Coenzymes Abbreviation Biochemical function Adenosine triphosphate ATP Donate phosphate, adenosine, and…
Some of the coenzymes possess nitrogenous bases, sugars, and phosphates. Such coenzymes are, therefore, referred to as nucleotide coenzymes. Examples: NAD+, NADP+, FMN, CoA, UDPG, and so on.
Not all coenzymes are vitamin derivatives; there are some other substances, which have no relation with vitamins but function as coenzymes. They may be considered as no vitamin coenzymes. Examples: ATP, CTP, and UTP. Refer Table 6.13.
Most of the coenzymes are the derivatives of water-soluble B-complex vitamins. Refer Table 6.12. Table 6.12 Coenzymes of B-complex Vitamins