FN3K catalyzes the phosphorylation of fructosamines which may result in deglycation, the non-enzymatic reaction of glucose with primary amines followed by Amadori re-arrangement. Phosphorylation of fructosamines may initiate metabolism of the modified amine and lead to the de-glycation of fructoselysine and of glycated proteins. Recombinant human FN3K protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.