Question 1

How is specificity determined by chymotrypsin?

Accepted Answer

A)  interaction of the active site amino acids with the substrate 
B)  binding of the N-terminus amino acid at the active site 
C)  covalent binding of a His residue to the substrate 
D)  large conformational change of a P-loop upon binding of substrate 
E)  binding of the proper amino acid into a deep pocket on the enzyme 
A)  interaction of the active site amino acids with the substrate 
B)  binding of the N-terminus amino acid at the active site 
C)  covalent binding of a His residue to the substrate 
D)  large conformational change of a P-loop upon binding of substrate 
E)  binding of the proper amino acid into a deep pocket on the enzyme

Question 2

What caused a "burst" of activity followed by a steady-state reaction when chymotrypsin was studied by stop-flow techniques?

Accepted Answer

Chymotrypsin cleaves peptide b

Question 3

Which amino acids in chymotrypsin are found in the active site and are participants in substrate cleavage?

Accepted Answer

A)  His, Ser, Asp 
B)  His, Ser 
C)  Asp, Lys 
D)  Lys, Arg 
E)  His, Ser, Arg 
A)  His, Ser, Asp 
B)  His, Ser 
C)  Asp, Lys 
D)  Lys, Arg 
E)  His, Ser, Arg

Question 4

Complete the structure of the catalytic triad of chymotrypsin by drawing the proper structure of the missing residue side chain in the box provided. Show the proper hydrogen bonding involved in this triad.

Accepted Answer

The answer of Complete the structure of the catalytic triad...

Question 5

What metal ion is required by carbonic anhydrase for activity?

Accepted Answer

A)  Zn2+ 
B)  Mg2+ 
C)  Cu2+ 
D)  Fe2+ 
E)  Ni2+ 
A)  Zn2+ 
B)  Mg2+ 
C)  Cu2+ 
D)  Fe2+ 
E)  Ni2+

Question 6

If you carried out site-directed mutagenesis of subtilisin, changing serine 221 to isoleucine, what would you expect?

Accepted Answer

A)  a large change in KM 
B)  a small change in KM  
C)  a large change in kcat 
D)  a large change in KM and a large change in kcat 
E)  a small change in KM and  a large change in kcat 
A)  a large change in KM 
B)  a small change in KM  
C)  a large change in kcat 
D)  a large change in KM and a large change in kcat 
E)  a small change in KM and  a large change in kcat

Question 7

The mechanism of chymotrypsin involves the formation of an unstable __________________ -shaped intermediate that is stabilized by the oxyanion hole.

Accepted Answer

The answer of The mechanism of chymotrypsin involves the formation...

Question 8

What process converts chymotrypsinogen to chymotrypsin?

Accepted Answer

A)  metal ion binding 
B)  peptide bond cleavage 
C)  coenzyme association 
D)  cysteine methylation 
E)  proline hydroxylation 
A)  metal ion binding 
B)  peptide bond cleavage 
C)  coenzyme association 
D)  cysteine methylation 
E)  proline hydroxylation

Question 9

How can covalent modification be used to determine the mechanism of action of an enzyme?

Accepted Answer

If a particular amino acid side chain is

Exam 9: Catalytic Strategies

How is specificity determined by chymotrypsin?

What caused a "burst" of activity followed by a steady-state reaction when chymotrypsin was studied by stop-flow techniques?

Which amino acids in chymotrypsin are found in the active site and are participants in substrate cleavage?

Complete the structure of the catalytic triad of chymotrypsin by drawing the proper structure of the missing residue side chain in the box provided. Show the proper hydrogen bonding involved in this triad.

What metal ion is required by carbonic anhydrase for activity?

If you carried out site-directed mutagenesis of subtilisin, changing serine 221 to isoleucine, what would you expect?

The mechanism of chymotrypsin involves the formation of an unstable __________________ -shaped intermediate that is stabilized by the oxyanion hole.

What process converts chymotrypsinogen to chymotrypsin?

How can covalent modification be used to determine the mechanism of action of an enzyme?

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