AK5, also known as adenylate kinase isoenzyme 5, is a member of the adenylate kinase family, which is involved in regulating the adenine nucleotide composition within a cell by catalyzing the reversible transfer of phosphate groups among adenine nucleotides. This member is related to the UMP/CMP kinase of several species. It is located in the cytosol and expressed exclusively in brain. Recombinant human AK5 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.