THE INFLUENCE OF PLURONICS AND THEIR CONJUGATES WITH PROTEINS ON THE RATE OF OXYGEN-CONSUMPTION BY LIVER-MITOCHONDRIA AND THYMUS LYMPHOCYTES

The membranotropic properties of block co-polymers and their protein c onjugates were studied by their effect on the rate of oxygen consumpti on by isolated liver mitochondria and on thymus-derived lymphocytes. T he block co-polymers consisted of poly(ethylene oxide) (PoE) [poly(eth ylene glycol)] and poly(propylene oxide) (PoP) to give either PoE-PoP or PoE-PoP-PoE. Both types inhibited uncoupled respiration of liver mi tochondria in a medium containing glutamate and malate and also of lym phocytes. They also uncoupled respiration in the presence of succinate in K+-containing medium and of lymphocytes. A method is described for linking protein to the block polymers to form conjugates. Such conjug ates were formed from alpha-chymotrypsin, BSA and cytochrome c(r) all of which produced similar effects on the respiration of the isolated m itochondria and lymphocytes. The data suggest that both the block cc-p olymers and their protein conjugates inhibit the NADH dehydrogenase co mplex and induce a K+-conductivity of the mitochondrial inner membrane ; the surface activity of the conjugates allows them to pass through t he plasma membrane and interact with the mitochondrial inner membrane.