Identification of Na+/K+-ATPase inhibitors in bovine plasma as fatty acids and hydrocarbons.
A preparative purification of endogenous inhibitors of the Na+/K+-ATPase has been carried out from bovine blood. Dried plasma was deproteinized, hexane-extracted and desalted, followed by further purification through a series of reverse-phase HPLC fractionations. Fractions active in inhibiting Na+/K+-ATPase activity and displacing ouabain were collected and purified further. By comparison with ouabain, the final extract was found to have a steeper concentration-effect curve in the inhibition of Na+/K+-ATPase. In displacement of [3H]ouabain, the extract had again a steeper concentration-effect curve than does ouabain, and in addition it enhanced ouabain binding at high dilutions. These properties are indicative of nonspecific interactions with the Na+/K+-ATPase. The active fraction was identified by TLC, HPLC, NMR, GLC and GC-MS, to be a mixture of three unesterified fatty acids, mainly oleic acid (72% of the total) and three saturated hydrocarbons. The assignment of structures was corroborated by comparison with authentic samples.
Tal
D M
DM
Department of Biochemistry, Weizmann Institute of Science, Rehovot, Israel.
Yanuck
M D
MD
van Hall
G
G
Karlish
S J
SJ
D000818:Animals; D002417:Cattle; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D004791:Enzyme Inhibitors / Q000097:blood*; D005227:Fatty Acids / Q000097:blood*; D008401:Gas Chromatography-Mass Spectrometry; D006838:Hydrocarbons / Q000097:blood*; D007679:Kidney Medulla / Q000201:enzymology; D010042:Ouabain / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013552:Swine
D004791:Enzyme Inhibitors; D005227:Fatty Acids; D006838:Hydrocarbons; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase