Cloning, purification and characterization of recombinant silkworm arginine kinase expressed in Escherichia coli

Arginine kinase (AK) is a major invertebrate phosphagen kinase that catalyzes the reversible transfer of high energy phosphoryl group of adenosine triphosphate (ATP) to arginine, yielding phosphoarginine and adenosine diphosphate. In this study, the 1068 bp open reading frame of a putative Bombyx mori arginine kinase gene (BmAK) was amplified from a pool of B. mori cDNAs and inserted into the prokaryotic expression plasmid pET-28a(+). The recombinant His-tagged BmAK protein was expressed in soluble form in Escherichia coli Rosetta and purified by metal chelating affinity chromatography. The amino acid sequence of recombinant protein was confirmed by mass spectroscopic analysis and the enzyme activity assay that indicated the recombinant protein was able to transfer the gamma phosphoryl group of ATP to arginine.