Nucleoside Diphosphate Kinase from Psychrophilic Pseudoalteromonas sp. AS-131 Isolated from Antarctic Ocean

Nucleoside diphosphate kinase isolated from psychrophilic Pseudoalteromonas sp. AS-131 (ASNDK) was expressed in Escherichia coli and purified to homogeneity. Comparing to mesophilic NDK isolated from Pseudomonas aeruginosa, ASNDK exhibited highly elevated thermolability: E. coli expression at 37 °C as a denatured insoluble form, 30 °C lower optimum temperature of enzymatic activity, and greatly reduced heat stability with 38 °C lower Tm value, fourfold higher Km and reduced Kcat/Km by 0.4-fold upon reaction temperature increase from 20 to 37 °C. The subunit structure of ASNDK was suggested to be dimer, as in NDKs isolated from moderate halophiles.