DETERGENT PROPERTIES OF WATER-SOLUBLE CHOLINE PHOSPHATIDES - SELECTIVE SOLUBILIZATION OF ACYL-COA-LYSOLECITHIN ACYLTRANSFERASE FROM THYMOCYTE PLASMA-MEMBRANES

  • 1 January 1979
    • journal article
    • research article
    • Vol. 254  (9) , 3652-3657
Abstract
Several analogs of lysolecithin solubilized human erythrocyte ghosts comparably or even better than other detergents. Derivatives with aliphatic chains of 12-14 C were most effective. The phosphorylcholine detergents apparently possess low protein-denaturing properties since they, for the first time, allowed the solubilization of enzymatically active acyl-CoA:lysolecithin acyltransferase from thymocyte plasma membranes. The solubilized enzyme was not sedimented at 177,000 .times. g for 60 min and penetrated into Sepharose 6B gels. Low detergent concentration resulted in a selective extraction of the acyltransferase (about 70%) as compared to alkaline phosphatase, nucleotide pyrophosphatase, .gamma.-glutamyltransferase or Mg2+-ATPase (30-40%). The selectivity was reflected in sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of soluble and sedimentable membrane fractions; 3 bands of approximately 53, 84 and 94 .times. 103 daltons were enriched in the supernatants, whereas 1 band of about 68 .times. 103 daltons was concentrated in the pellet. The preferential extraction of acyltransferase may be related to particularly high affinity of lysolecithin analogs for this enzyme, which at higher concentrations was competitively inhibited by these detergents. The inhibitor constants ranged from 1400 .mu.M for the C10 analog (ET-10-H) to 80 .mu.M for the compound with 16 carbons (ET-16-H) per aliphatic chain.