Biochemical properties of purified human retinol dehydrogenase 12 (RDH 12): Catalytic efficiency toward retinoids and C9 aldehydes and effects of cellular retinol-binding protein type I (CRBPI) and cellular retinaldehyde-binding protein (CRALBP) on the oxidation and reduction of retinoids

Academic Article

Abstract

  • Retinol dehydrogenase 12 (RDH12) is a novel member of the short-chain dehydrogenase/reductase superfamily of proteins that was recently linked to Leber's congenital amaurosis 3 (LCA). We report the first biochemical characterization of purified human RDH12 and analysis of its expression in human tissues. RDH12 exhibits ∼2000-fold lower Km values for NADP + and NADPH than for NAD+ and NADH and recognizes both retinoids and lipid peroxidation products (C9 aldehydes) as substrates. The kcat values of RDH12 for retinaldehydes and C 9 aldehydes are similar, but the Km values are, in general, lower for retinoids. The enzyme exhibits the highest catalytic efficiency for all-trans-retinal (kcat/Km ∼900 min-1 μM-1), followed by 11-cis-retinal (450 min -1 mM-1) and 9-cis-retinal (100 min-1 mM -1). Analysis of RDH12 activity toward retinoids in the presence of cellular retinol-binding protein (CRBP) type I or cellular retinaldehyde-binding protein (CRALBP) suggests that RDH12 utilizes the unbound forms of all-trans- and 11-cis-retinoids. As a result, the widely expressed CRBPI, which binds all-trans-retinol with much higher affinity than all-trans-retinaldehyde, restricts the oxidation of all-trans-retinol by RDH12, but has little effect on the reduction of all-trans-retinaldehyde, and CRALBP inhibits the reduction of 11-cis-retinal stronger than the oxidation of 11-cis-retinol, in accord with its higher affinity for 11-cis-retinal. Together, the tissue distribution of RDH12 and its catalytic properties suggest that, in most tissues, RDH12 primarily contributes to the reduction of all-trans-retinaldehyde; however, at saturating concentrations of peroxidic aldehydes in the cells undergoing oxidative stress, for example, photoreceptors, RDH12 might also play a role in detoxification of lipid peroxidation products. © 2005 American Chemical Society.
  • Authors

    Published In

  • Biochemistry  Journal
  • Digital Object Identifier (doi)

    Author List

  • Belyaeva OV; Korkina OV; Stetsenko AV; Kim T; Nelson PS; Kedishvili NY
  • Start Page

  • 7035
  • End Page

  • 7047
  • Volume

  • 44
  • Issue

  • 18