The Mammalian Cytosolic Type 2 (R)-β-hydroxybutyrate Dehydrogenase (BDH2) is 4-oxo-L-proline Reductase (EC 1.1.1.104)

Abstract

The early studies on chicken embryos revealed that exposition to 4-oxo-L-proline resulted in the explicit increase in 4-hydroxy-L-proline content in their tissues. In 1962, 4-oxo-L-proline reductase, an enzyme responsible for the reduction of 4-oxo-Lproline, was partially purified from rabbit kidneys and characterized biochemically, but only recently the molecular identity of the enzyme has been unveiled in our laboratory. The present investigation reports the purification, identification as well as biochemical characterization of 4-oxo-Lproline reductase. The enzyme was purified from rat kidneys about 280-fold. Following mass spectrometry analysis of the purified protein preparation, the mammalian cytosolic type 2 (R)-β- hydroxybutyrate dehydrogenase (BDH2) emerged as the only meaningful candidate for the reductase.