The following reaction depicts the activity of a particular class of enzymes : [Figure: X and Y are substituents on a C-C bond. Substrate (X-C-C-Y) is converted by enzyme E to products X-Y and C=C]. Identify the enzymes class 'E' from the following options :

Solution & Explanation

Answer: (C) Lyases. Solution: The figure shows a substrate X−C−C−Y losing the groups X and Y (as X−Y) to leave a C=C double bond, without using water. NCERT defines lyases as enzymes that catalyse removal of groups from substrates by mechanisms other than hydrolysis, leaving double bonds — exactly this reaction. Transferases transfer groups, isomerases rearrange isomers, and ligases join molecules, so none of those match. NCERT Reference: Ch 9, p.117, line ~34 — "Lyases: Enzymes that catalyse removal of groups from substrates by mechanisms other than hydrolysis leaving double bonds."