Enzymes – Section 1

11. The cleavage specificity of trypsin and chymotrypsin depend in part on the

A. proximity of Ser 195 to the active site or specificity pocket
B. size, shape, and charge of the active site or specificity pocket
C. presence of a low-barrier hydrogen bond in the active site or specificity pocket
D. absence of water in the active site

Correct Answer: B. size, shape, and charge of the active site or specificity pocket

12. The E.coli pyruvic acid dehydrogenase complex is reported to

A. decatalyze the oxidation of pyruvic acid to acetyl Co A and CO2
B. Catalyze the oxidation of pyruvic acid to acetyl Co A and CO2
C. retard the reduction of pyruvic acid to acetyl Co A and CO2
D. Catalyze the reduction of pyruvic acid to acetyl Co A and CO2

Correct Answer: B. Catalyze the oxidation of pyruvic acid to acetyl Co A and CO2

13. Which of the common features are shared between serine and aspartate proteases?

A. Both require water to complete the catalytic cycle
B. Both use a base to activate the nucleophile
C. Both show specificity for certain amino acid sequences
D. All of the above

Correct Answer: D. All of the above

14. Before they can react, many molecules need to be destabilized. This state is typically achieved through

A. changing the three-dimensional shape of the molecule
B. oxidizing the molecules by removing electrons
C. changing the reaction from a biosynthetic to a catabolic pathway
D. the input of a small amount of activation energy

Correct Answer: D. the input of a small amount of activation energy

15. Common feature in all serine proteases is a

A. hydrophobic specificity pocket
B. hydrophilic specificity pocket
C. cluster of reactive serine residues
D. single reactive serine residue

Correct Answer: D. single reactive serine residue

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