EFFECT OF CONJUGATES OF BOVINE SERUM-ALBUMIN WITH POLYALKYLENE OXIDESON RESPIRATION OF HEART-MITOCHONDRIA

The effect of polyalkylene oxides and block copolymers of ethylene oxi de and propylene oxide (proxanols, pluronics) and their conjugates wit h bovine serum albumin (BSA) on respiration and oxidative phosphorylat ion in rat heart mitochondria has been studied. The proxanols and thei r conjugates with BSA stimulate respiration of mitochondria in state 4 , inhibit respiration in state 3 and 2,4-dinitrophenol-uncoupled state respiration, decrease the values of respiratory control and ADP/O rat io, and display weak uncoupling properties. The proxanols inhibit resp iration and oxidative phosphorylation more effectively than their conj ugates with BSA. The effect of the conjugate on the mitochondrial memb rane is reversible, in contrast to that of the proxanols. The studied compounds act preferentially on the NADH dehydrogenase complex of the respiratory chain. Inhibition of respiration in thymocytes by these co mpounds confirms their ability to penetrate the cell membrane. The dep endence of membranotropic properties of polyalkylene oxides and the co njugates on their structure is discussed.