Substrate Specificity of Rat Plasma Lecithin-cholesterol Acyltransferase towards a Molecular Species of Phosphatidylcholine
Author(s) -
Yoshifumi Hida,
Yuji FURUKAWA,
Takashi Urano,
Hyoun Ju Kim,
Shuichi Kimura
Publication year - 1993
Publication title -
bioscience biotechnology and biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.509
H-Index - 116
eISSN - 1347-6947
pISSN - 0916-8451
DOI - 10.1271/bbb.57.1111
Subject(s) - phosphatidylcholine , yolk , lecithin , substrate (aquarium) , vesicle , enzyme , enzyme assay , chemistry , biochemistry , egg lecithin , chromatography , biology , phospholipid , membrane , food science , ecology
The substrate specificity and the affinity of rat purified lecithin-cholesterol acyltransferase towards the molecular species of phosphatidylcholine (PC) were studied in comparison with the human enzyme. The substrate vesicles were prepared with 40% of a test PC, 60% of egg yolk PC, and tritium cholesterol. Both human and rat enzymes showed similar high reactivity to the substrates containing three major PCs (16: 0-18: 1 PC, 16: 0-18: 2 PC, and 18: 0-18: 1 PC) of egg yolk compared with the vesicles of egg yolk PC alone. In the case of 18: 0-20: 4 PC, the rat enzyme had the highest activity among all the test PCs, but the human enzyme only had a moderate activity. Even when the substrate consisted of 18: 0-20: 4 PC alone, the rat enzyme had a high activity, but the activity of the human enzyme was not detected. Symmetrical diacyl-PCs (18: 2-18: 2 PC, 18: 1-18: 1 PC, 18: 0-18: 0 PC) were not a preferable substrate for either enzyme. The transfer of both the human and rat enzymes from the vesicles containing 18: 0-20: 4 PC to the egg yolk PC vesicles was on a higher level than that from the vesicles containing 18: 2-18: 2 PC. This suggests that the activity of the LCA T can be easily influenced by the kinds of PC molecular species and its relative content in the substrate and that the substrate may provide the extent of the enzyme transfer between the substrate particles.
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