[Kinetic properties of blood plasma lecithin cholesterol acyltransferase in persons with hyper-alpha-lipoproteinemia].
A study was made of the kinetics of the lecithin-cholesterol-acyltransferase reaction (LCAT-reaction) according to the substrate, nonesterified cholesterol of high density lipoproteins (HDLP) and of the effect produced by the medium pH and apoprotein E (apo-E) on the rate of the LCAT-reaction in blood plasma of subjects with hyper-alpha-lipoproteinemia. HDLP isolated from blood plasma of subjects with hyper-alpha-lipoproteinemia were used as substrate. Infranatants obtained from blood plasma of the test subjects after removing all lipoproteins with a density of 1.21 g/ml served as a source of the enzyme. The kinetic curve of the rate of the LCAT-reaction with one or two plateaus was found to be complex in nature; pH 7.4 and 8.0 were found to be optimal for the LCAT-reaction at high and low concentrations of HDLP, respectively. At a low HDLP concentration apo-E had no remarkable effect on the rate of the LCAT-reaction, while at a high HDLP concentration the rate of the LCAT-reaction was increased. It is assumed that more than two isoforms of LCAT are present in blood plasma of subjects with hyper-alpha-lipoproteinemia.
D000328:Adult; D008076:Cholesterol, HDL / Q000097:blood; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006951:Hyperlipoproteinemias / Q000201:enzymology*; D007527:Isoenzymes / Q000097:blood; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000097:blood*; D008297:Male; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000097:blood*; D013379:Substrate Specificity
D008076:Cholesterol, HDL; D007527:Isoenzymes; D008075:Lipoproteins, HDL; D007862:Phosphatidylcholine-Sterol O-Acyltransferase
Nekotorye kineticheskie svoĭstva letsitin-kholesterin-atsiltransferazy plazmy krovi lits s giper-al'fa-lipoproteidemii.