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 conjugates were studied by their effect on the rate of oxygen consumption by isolated liver mitochondria and on thymus-derived lymphocytes. The block co-polymers consisted of poly(ethylene oxide) (PoE) [poly(ethylene glycol)] and poly(propylene oxide) (PoP) to give either PoE-PoP or PoE-PoP-PoE. Both types inhibited uncoupled respiration of liver mitochondria in a medium containing glutamate and malate and also of lymphocytes. 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 conjugates were formed from alpha-chymotrypsin, BSA and cytochrome c, all of which produced similar effects on the respiration of the isolated mitochondria and lymphocytes. The data suggest that both the block co-polymers and their protein conjugates inhibit the NADH dehydrogenase complex and induce a K(+)-conductivity of the mitochondrial inner membrane; the surface activity of the conjugates allows them to pass through the plasma membrane and interact with the mitochondrial inner membrane.