NADPH-CONTAINING SUPEROXIDE-PRODUCING LIPOPROTEIN FRACTION OF BLOOD-SERUM - ISOLATION, PURIFICATION, BRIEF CHARACTERIZATION, AND MECHANISM OF ACTION

A water-soluble NADPH-containing lipoprotein fraction (suprol) was iso lated from human and animal (bovine, rabbit, and rat) sera and purifie d. After binding with trivalent iron ions, the fraction generates supe roxide radicals (O-2(-)) under aerobic conditions at physiologic pH. T he isolation and purification were carried out using ion-exchange chro matography on DEAE- and CM-cellulose and DEAE-Sephadex and gel filtrat ion on Sephadex G-150 and P-150 biogel. The optical purity index of th e purified fraction (A(280)/A(430)) was 8.5. The fraction has an optic al absorption spectrum with maximum at 280 nm and a weak band at 430 n m and a fluorescence spectrum with excitation maximum at 370 nm and em ission maximum at 430 nm characteristic of NADPH. The fraction contain s about 50% phospholipid by weight and thus seems to be an NADPH-conta ining lipoprotein. The mechanism of O-2(-) generation is supposed to i nclude the reduction of Fe3+ to Fe2+ by the NADPH group and electron t ransfer from Fe2+ to atmospheric oxygen. Suprol appears to be a simple and available source of superoxide radicals for the study of their in fluence on various biosystems.