Purification and characterization of human brain serine racemase expressed in moderately halophilic bacteria.

We have successfully expressed an active human brain serine racemase (hSR) with His-tag using moderate halophile. The purified His-hSR showed high elimination and racemization activities on L-serine: the elimination activity was 2.6-fold higher than racemization activity. Both enzyme activities showed an optimum reaction pH at around 9.0 and were stimulated 5- to 7-fold by such divalent cations as Mg++, Mn++ and Ca++.