Aggregation of submitochondrial particles by heparin and its application to the study of carnitine transport.
A novel technique for the separation of submitochondrial particles from the external medium, an essential procedure in transport studies, was devised. Very low concentrations of heparin (5-10 micrograms/ml) aggregate the particles and permit their rapid sedimentation in a micro-centrifuge. The transfer of activated fatty acids into mitochondria for oxidation depends on the exchange of matrix carnitine for external fatty-acylcarnitine. To study the matrix face of the carnitine/acylcarnitine translocase, inverted submitochondrial particles were prepared and loaded with L-[14C]carnitine. As found in intact mitochondria, the Km value for L-carnitine was 8 mM, that for palmitoyl-L-carnitine was two orders of magnitude lower, and 11-trimethylaminoundecanoyl-DL-carnitine was a competitive inhibitor. The properties of the carrier exposed to the outer and to the matrix sides of the mitochondrial inner membrane are thus similar.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002331:Carnitine / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D002417:Cattle; D002458:Cell Fractionation / Q000379:methods*; D006493:Heparin / Q000494:pharmacology*; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism; D010172:Palmitoylcarnitine / Q000494:pharmacology; D013367:Submitochondrial Particles / Q000187:drug effects / Q000378:metabolism
D010172:Palmitoylcarnitine; C013723:11-trimethylaminoundecanoyl-L-carnitine; D006493:Heparin; D002331:Carnitine