DISTRIBUTION OF PHOSPHOLIPIDS, FATTY-ACIDS, AND PLATELET FACTOR-3 ACTIVITY AMONG SUBCELLULAR-FRACTIONS OF HUMAN PLATELETS

  • 1 January 1976
    • journal article
    • research article
    • Vol. 47  (6) , 963-971
Abstract
As compared with other methods, this method for subcellular fractionation of human platelets improved the separation of mitochondria, .alpha. granules and lysosomal enzyme activities. In the .alpha. granule zone, plasmalogen phosphatidyl ethanolamine peaked at the expense of diacyl phosphatidyl ethanolamine. The fatty acid composition of the membrane lysophosphatidyl choline suggested that it may have been formed by the action of platelet phospholipase A2 activity. The fatty acids of the membranes showed a markedly asymmetrical distribution in noncholine vs. choline phospholipids. The latter held 94%, 72% and 85%, respectively, of the total content of 16:0, 18:1 and 18:2 fatty acids, but 55% of the 18:0, 72% of 20:4 and 67% of higher polyenoic acids other than 20:4 were esterified to the non-choline group. Clot-promoting activity, on the basis of protein content, was highest in the membrane fractions, but on the basis of phospholipid content, in the nonmembranous fractions. The discussion centers on possible explanations for this novel finding.

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