NaCl-activated nucleoside diphosphate kinase from extremely halophilic archaeon, Halobacterium salinarum , maintains native conformation without salt

Enzymes from extremely halophilic archaea are readily denatured in the absence of a high salt concentration. However, we have observed here that a nucleoside diphosphate kinase prepared from Halobacterium salinarum was active and stable in the absence of salt, though it has the amino acid composition characteristic of halophilic enzymes. Recombinant nucleoside diphosphate kinase expressed in Escherichia coli requires salt for activation in vitro, but once it acquires the proper folding, it no longer requires the presence of salts for its activity and stability.