9] Detergent-solubilized NADH-cytochrome b5 reductase

Abstract

Publisher Summary This chapter talks about solubilized NADH-cytochrome b5 reductase protein. NADH-cytochrome b5 reductase is a flavoprotein that is tightly bound to the membranes of endoplasmic reticulum (microsomes) and outer mitochondrial membrane of liver and many other tissues. It catalyzes the NADH-dependent reduction of cytochrome b5 and several artificial electron acceptors, such as ferricyanide and 2, 6-dichlorophenolindophenol. Despite the fact that the reductase purified after lysosomal solubilization retains the flavin prosthetic group as well as catalytic activities, the possibility exists that it is proteolytically modified product of the native flavoprotein. This is especially likely in view of the finding that proteolytically solubilized cytochrome b5 is a heme-containing fragment of the native hemoprotein, which can be purified only after solubilization with detergents. It is clear that the proteases remove a peptide segment that is hydrophobic and is responsible for the membrane binding and reconstitution capacity from the native reductase molecule.