ISSN:
1432-1424
Schlagwort(e):
Key words: Arachidonate — Palmitate — oleate — red cell membrane — transport site specificities
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Chemie und Pharmazie
Notizen:
Abstract. We studied the specificities of human red cell membrane bindings of three long chain fatty acids, palmitic- arachidonic- and oleic acid, using resealed membranes, ghosts. Previously estimated binding capacities, affinities and inside/outside distributions [6, 10, 11, 12], suggest separated binding sites. This possibility is explored by estimating the binding properties of one fatty acid in the presence of one or two of the others. Binding capacities, nmol g−1 ghosts, of palmitic and arachidonic acid estimated simultaneously vs. separately are 27.4 ± 2.7 vs. 29.0 ± 2.1 (P 〈 0.6) and 6.5 ± 0.6 vs. 5.5 ± 0.5 (P 〈 0.2) respectively. The corresponding estimates for oleic- and palmitic acid are 36.5 ± 2.0 vs. 34.0 ± 2.2 (P 〈 0.4) and 28.4 ± 1.8 versus 29.1 ± 2.1 (P 〈 0.8). The binding sites are therefore independent. For each of the three fatty acids in the absence or in the presence of one or two of the others, the inside/outside distributions of the binding sites and the membrane transfer rate constants are elucidated by exchange efflux kinetics at 0°C from ghosts with and without enclosed albumin. Packed ghosts loaded with radioactive acids are injected rapidly into a large volume of vigorously stirred buffer with albumin. With a resolution time of about 1-sec serial filtered ghost-free aliquots are collected and counted. The analyses show that palmitic- and oleic acid sites of transport are entirely independent but do not exclude that palmitic- and/or oleic acid binding may diminish the arachidonic acid affinity a little. The diversity combined with specificity suggests that the transport sites for long chain fatty acids are protein-determined microdomains of phospholipids.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/s002329900025
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