Organic Chemistry

Section 24.9 Enzyme-Catalyzed Reactions 1021

CH 2

CH 2

CH 2

CH 2

CH 2 CH 2

CH 2

CHC NH + H 2 O CHC O + H 3 N

H

Gly

193

Ser

195

Asp

102

His

57

O

O

C

O

H C

HC

NH CH

O N

N

H

O

O

O

chymotrypsin

hydrophobic

pocket

HN N

Overall Reaction

CH 2

CH 2

CH 2

CH 2

H

Gly

193

Ser

195

Asp

102

His

57

O

O

C O

C

H

HC

NH

O N

N

H

HNN

oxyanion

hole

CH 2

CH 2

CH 2

CH 2

H

Gly

193

Ser

195

Asp

102

His

57

O

O

C O

C

H

HC

HO CH

O N

N

H

HNN

CH 2

CH 2

CH 2

H

Gly

193

Ser

195

Asp

102

His

57

O

O

C

H

HC

O CCH

O N

N

H

N

CH 2

CH 2

CH 2

NH CH^2

2

H

Gly

193

Ser

195

Asp

102

His

57

O

O

C O

C

H

H

HC

O CH

O N

N

H

HN N

HN

+

NH 3 NH 2

+

CH

acyl-enzyme

intermediate

Figure 24.7
Proposed mechanism for the chymotrypsin-catalyzed hydrolysis of a peptide bond.