Explain5 marksChallenge
A newly discovered enzyme, cellulase X, hydrolyses cellulose into glucose. It also shows weak hydrolytic activity on hemicellulose, a polysaccharide similar in structure to cellulose. The active site of cellulase X is a deep groove lined with catalytic amino acids. Researchers propose that the active site is flexible.
Explain how the lock-and-key and induced-fit hypotheses differ in their predictions about the specificity of cellulase X, and how the weak activity on hemicellulose supports the induced-fit hypothesis. In your answer, describe how a colorimeter could be used to measure the rate of hydrolysis of a synthetic substrate, p-nitrophenyl-β-D-glucoside, which releases a yellow product upon hydrolysis.