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Table 3 Activity of the wild type and mutant enzymes.

From: Aminopeptidase B, a glucagon-processing enzyme: site directed mutagenesis of the Zn2+-binding motif and molecular modelling

Mutation site

Number of mutants

Mutated codon

Mutants

Percentage of activity

H325

 

CAC

Wild type

100

 

3

CAT

H

100

 

2

TAT

Y

0

 

5

GCC

A

0

 

6

TTC

F

0

E326

 

GAG

Wild type

100

 

2

GAA

E

100

 

2

GCG

A

0

 

4

CAA

Q

0

 

3

GAT

D

0

 

7

CAT

H

0

H329

 

CAC

Wild type

100

 

3

CAT

H

100

 

4

GCC

A

0

 

3

TAT

Y

0

 

4

TTC

F

0

E348

 

GAA

Wild type

100

 

8

GAG

E

100

 

1

CAG

Q

0

 

2

GAC

D

0

 

4

GCG

A

0

 

3

CAC

H

0

  1. The number of mutants analysed, the mutated codon and its corresponding amino acid, as well as the percentages of enzyme activity are indicated. The position in the rat Ap-B sequence of the targeted amino acid is numbered. The percentage of activity was determined using L-Arg β-NA as substrate. Activity assays were performed in triplicate with enzymes collected from both purification methods.