Immunoreactivity of recombinant human ADP-ribosylarginine hydrolase

ADP-ribosylarginine hydrolase (AAH) has not been detected yet in human tissues with anti-AAH antibodies. Those failure in human AAH (hAAH) detection are possibly because hAAH is not recognized with the only available antibodies, rabbit antirat AAH (rAAH) polyclonal antibodies or amounts of AAH in human tissues are too small to be detected with the antibodies. To clarify the interaction between hAAH and anti-rAAH antibodies, purified authentic hAAH is necessary. In this study, the protein was expressed as a histidine-tagged recombinant protein in Escherichia coli and purified to apparent homogeneity by a metal chelation chromatography. The purified protein, similar in properties to hAAH reported previously, catalyzed the glycohydrolysis of ADP-ribosylarginine. On Western blotting, the antirAAH antibodies interacted with hAAH, but not so strongly as with the rat hydrolase. Thus, anti-hAAH antibodies are needed to detect trace amounts of the antigen in human tissues.