AbstractsBiology & Animal Science

Enzymes involved in the repair of hydrated forms of NADH and NADPH : identification, characterization and subcellular distribution

by Alexandre Marbaix

Institution: Université Catholique de Louvain
Department: Institut de Duve
Year: 2015
Keywords: Dehydration; Epimerisation; Metabolite repair; NADHX; NADPHX
Record ID: 1076595
Full text PDF: http://hdl.handle.net/2078.1/158736


NADH and NADPH may undergo a hydration reaction that converts them to damaged forms, named NADHX and NADPHX and existing as two different, (S) and (R) epimers. This hydration reaction is spontaneous or enzyme-catalysed, being then due to the side-activity of glyceraldehyde-3-phosphate dehydrogenase. NADHX and NADPHX do not function anymore as coenzymes, but rather as inhibitors of several dehydrogenases. This work shows the existence of an extremely conserved enzymatic system that catalyses the repair of the two NAD(P)HX epimers. It consists of an ATP- or ADP-dependent dehydratase, which specifically acts on the (S) epimer, and an epimerase, which catalyses the interconversion of the (R) and (S) epimers. In addition, we show that, in mammals, the two enzymes are ubiquitous and present in the major NAD(P)H-containing subcellular compartments, and that their endogenous activity is sufficient to cope with NAD(P)HX formation in cells. (BIFA - Sciences biomédicales et pharmaceutiques)  – UCL, 2015