NADH-ferric reductase activity associated with dihydropteridine reductase.

P L Lee, C Halloran, A R Cross, E Beutler

Department of Molecular and Experimental Medicine, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA. plee@scripps.edu

Biochemical and biophysical research communications 2000 May 19

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In mammals dietary ferric iron is reduced to ferrous iron for more efficient absorption by the intestine. Analysis of a pig duodenal membrane fraction revealed two NADH-dependent ferric reductase activities, one associated with a b-type cytochrome and the other not. Purification and characterization of the non-cytochrome ferric reductase identified a 31 kDa protein. MALDI-MS analysis and amino acid sequencing identified the ferric reductase as being related to the 26 kDa liver NADH-dependent quinoid dihydropteridine reductase (DHPR). The NADH-dependent DHPR ferric reductase activity was found to be pteridine-independent since exhaustive dialysis did not reduce activity and heat-inactivation destroyed activity. In intestinal Caco-2 cells, DHPR mRNA levels were found to be regulated by iron. Thus, DHPR appears to be a dual function enzyme, a NADH-dependent dihydopteridine reductase and an iron-regulated, NADH-dependent, pteridine-independent ferric reductase. Copyright 2000 Academic Press.

Citation

P L Lee, C Halloran, A R Cross, E Beutler. NADH-ferric reductase activity associated with dihydropteridine reductase. Biochemical and biophysical research communications. 2000 May 19;271(3):788-95