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Table 2 Kinetic parameters of substrate hydrolysis by chitinase A wild-type and mutants. A kinetic study was carried out using 0–5% (w/v) colloidal chitin and 0–500 μM chitohexaose as substrates. After 10 minutes of incubation at 37°C, the amounts of the reaction products were determined from a standard curve of [GlcNAc]2

From: The effects of the surface-exposed residues on the binding and hydrolytic activities of Vibrio carchariae chitinase A

Chitinase A variant

Chitohexaose

Colloidal chitin

 

Km(μM)

kcat (s-1)

kcat/ Km(s-1M-1)

Km(101 mg ml-1)

kcat (s-1)

k cat / Km(10-1 s-1/mg ml-1)

Wild-type

218 ± 22.0

2.9

1.3 × 103 (100)a

1.74 ± 0.1

1.2

0.7 (100)

S33A

171 ± 20.5

2.6

1.5 × 103 (115)

2.07 ± 0.2

0.9

0.4 (57)

S33W

210 ± 15.4

2.8

1.3 × 103 (100)

1.58 ± 0.2

1.4

0.9 (129)

W70A

185 ± 22.0

2.5

1.3 × 103 (100)

2.26 ± 0.4

0.4

0.2 (29)

W231A

189 ± 13.2

2.6

1.4 × 103 (108)

1.01 ± 0.2

0.6

0.6 (86)

W231F

163 ± 10.3

2.4

1.5 × 103 (115)

1.70 ± 0.2

0.9

0.5 (71)

Y245W

201 ± 13.1

2.6

1.3 × 103 (100)

1.82 ± 0.2

1.7

0.9 (129)

  1. a Relative catalytic efficiencies (%) are shown in parentheses.
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BMC Biochemistry

ISSN: 1471-2091

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