Different arachidonate and palmitate binding capacities of the human red cell membrane.
Human red cell membrane bindings of arachidonate and palmitate at pH 7.3 are investigated at temperatures between 0 and 38 degrees C by equilibrating ghosts with the long-chain fatty acids bound to bovine serum albumin in molar ratios (v) within the physiological range (< 1.7). Linearized relations of ghost uptakes and fatty acid monomer concentrations in buffer provide estimates of the binding capacities and corresponding equilibrium dissociation constants (Kdm). The temperature-independent arachidonate binding capacity, 5.5 +/- 0.5 nmol g-1 packed ghosts, is approximately fivefold smaller than that of palmitate, 26.6 +/- 2.0 nmol g-1. While Kdm of arachidonate binding 5.1 +/- 0.5 nM is temperature independent, Kdm of palmitate increases with temperature from 3.7 nM at 0 degrees C to 12.7 nM at 38 degrees C. The large difference in binding capacities suggests the presence of at least two different fatty acid binding domains in human red cell membranes.
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Department of Medical Biochemistry and Genetics, University of Copenhagen, Panum Institute, Denmark.
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D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002417:Cattle; D004910:Erythrocyte Membrane / Q000378:metabolism*; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009363:Neoplasm Proteins; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism*; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013696:Temperature; D025521:Tumor Suppressor Proteins
D002352:Carrier Proteins; C107608:FABP7 protein, human; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D009363:Neoplasm Proteins; D010169:Palmitic Acids; D025521:Tumor Suppressor Proteins; D012710:Serum Albumin, Bovine; D016718:Arachidonic Acid; D019308:Palmitic Acid