D-gluconate kinase, thermosensitive, also known as idnk, D-gluconate kinase, thermosensitive, also known as idnk, is a 187 amino acid protein that belongs to the gluconokinase gntK/gntV family and catalyzes the conversion of ATP and D-gluconate to ADP and 6-phospho-D-gluconate. This protein is thought to play a role in gender determination, deletion of the distal portion of 9p can lead to development of male to female sex reversal, the phenotype of a female with a male X, Y genotype. Recombinant E.coli idnk protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.