Enzymes are proteins that catalyse biological reactions. These enzymes are grouped or categorized as per their reaction mechanism. They are divided in 6 classes.

$1$ - Oxidoreductase/dehydrogenase - catalyse oxidoreduction reaction.

$2$ - Transferase - Cataysing transfer of functional group

$3$ - Hydrolases - Catalyses hydrolysis of compounds.

$4$ - Lyases - catalyses removal of groups by mechanism other than hydrolysis

$5$ - Isomerases - Catalysing inter conversion of isomers

$6$ - Ligases - catalysing linking of two compounds.

Enzyme $4\mathrm{ }\mathrm{a}.\mathrm{b}.\mathrm{c}$ . belongs to the group of lyases which catalyses break down of substrates by means other than hydrolysis.