THE ROLE OF CALCIUM-IONS AND BILE-SALTS ON THE PANCREATIC LIPASE-CATALYZED HYDROLYSIS OF TRIGLYCERIDE EMULSIONS STABILIZED WITH LECITHIN
THE ROLE OF CALCIUM-IONS AND BILE-SALTS ON THE PANCREATIC LIPASE-CATALYZED HYDROLYSIS OF TRIGLYCERIDE EMULSIONS STABILIZED WITH LECITHIN
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DOI：
10.1023/a:1015956104500
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发表时间：
1989-06-01
影响因子：
3.7
通讯作者：
STELLA, VJ
中科院分区：
文献类型：
--
作者：
ALVAREZ, FJ;STELLA, VJ
Lecithin-stabilized triglyceride emulsions are subject to hydrolysis by pancreatic lipase. The time profiles of these reactions are characterized by a lag-phase and a zero-order phase. Lag phases are more pronounced with long-chain triglycerides. Ca2+ is effective in reducing the lag-phase and activating lipase. Kinetic analysis of the reactions suggests that, like previous findings by others, taurodeoxycholate (TDC) micellar solutions combine with the lipase-colipase complex to form another catalytically active enzyme form. This enzyme form exhibits reduced activity in the absence of Ca2+. In the presence of Ca2+ the mixed micelle-lipase complex becomes more active and opens a new pathway for lipolysis. It is suggested that this enzyme form can bind more easily to interfaces with different physicochemical properties. Under these conditions, Ca2+ activates the lipoplysis of short-, medium-, and long-chain triglycerides by a similar mechanism. Maximum activities were measured in the presence of approximately 6 mM TDC and 30 mM Ca2+. The experimental conditions approximate the physiological conditions in the gastrointestinal tract since all of the factors studied here have been reported to be necessary for in vivo lipolysis and/or absorption of triglycerides. A mechanistic model for lipolysis in the presence of Ca2+ and the bile salt TDC is proposed which accounts for most of the experimental observations in a quantitative manner.
