Studies on Bile-sensitive Lipase. IX. Action Pattern and Mechanism of Lipolysis by Mucor Lipase
1971 年 19 巻 12 号 p. 2457-2465
詳細
1971 年 19 巻 12 号 p. 2457-2465
To clarify the hydrolysis rate of esters at each position of triglyceride (TG), the positional specificity and mechanism of lipolysis by Mucor lipase, kinetic studies and action pattern of hydrolysis on glycerides were studied. It was found by thin-layer chromatography that the lipase firstly hydrolyzed the esters at outer position of TG and next the inner chain, and the hydrolysis rate of esters was in the order : TG>2, 3-DG≒MG, however, in the presence of bile salts : TG>2, 3-DG>MG. Although in the presence of bile salts the rate at initial stage of lipolysis was higher than that in its absence, the rate at the end became equal to or less than that in its absence. Thermodynamic values of activation state little changed by the addition of the salts. Km and Vmax values were found to be 7.4×10-3M and 10.8 μmoles/min for trilaurin and 26.7×10-3 and 8.1 for 1, 3-dilaurin, respectively. k values for TG were also higher than that for 1, 3-DG. Km values for triolein and trilinolein were 6.3×10-2 and 6.5×10-2M, respectively, whereas the value for trilinolenin (Δ6, 7, Δ9, 10 and Δ12, 13) was 48×10-2M and the result indicates that polyunsaturated fatty acids in TG molecules resist the lipolysis.
