Hydrolysis of galactolipids by human pancreatic lipolytic enzymes and duodenal contents.
Hydrolysis of galactolipids by human pancreatic lipolytic enzymes and duodenal contents.
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人胰腺脂肪分解酶和十二指肠内容物水解半乳糖脂。
DOI：
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发表时间：
1995
影响因子：
6.5
通讯作者：
A. Nilsson
中科院分区：
文献类型：
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作者：
L. Andersson;C. Bratt;K. Arnoldsson;B. Herslöf;N. U. Olsson;B. Sternby;A. Nilsson
单半乳糖基二酰基甘油（MGDG）、二半乳糖基二酰基甘油（DGDG）和磺基奎诺基二酰基甘油（SQDG）是植物性食品中的主要脂质。它们的消化和吸收尚不清楚。本研究考察了人十二指肠内容物、胰液和纯化的人胰腺脂肪酶对半乳糖脂的体外水解情况。将半乳糖脂与人十二指肠内容物、胰液、纯胰腺羧基酯脂肪酶 (CEL) 以及辅脂肪酶依赖性脂肪酶与辅脂肪酶 (Lip-Col) 一起孵育。通过使用[3H]半乳糖或[3H]脂肪酸标记的DGDG，将水解估计为游离脂肪酸的释放。胰液和十二指肠内容物将 DGDG 水解为脂肪酸、二半乳糖基单酰基甘油 (DGMG) 和水溶性含半乳糖的化合物。 DGDG 的水解依赖于胆汁盐，最适 pH 值为 6.5-7.5。人胰液从 MGDG、DGDG 和 SQDG 中释放脂肪酸。纯化的 CEL 水解了所有三种底物；水解率MGDG>SQDG>DGDG。纯 Lip-Col 对 MGDG 有活性，但对 DGDG 几乎没有活性。通过 Sephadex G100 凝胶过滤色谱法分离胰液，发现两个具有半乳糖脂酶活性的峰，与 CEL（分子量 100 kD）和脂肪酶（分子量 50 kD）峰一致。与纯 Lip-Col 相比，后一个峰的酶对 DGDG 的活性与对 MGDG 的活性一样。因此，DGDG被CEL和分子量为40-50kD的胰酶水解成脂肪酸和溶血DGDG。 MGDG、DGDG和SQDG均被人胰液水解。纯 CEL 水解所有三种底物。
Monogalactosyldiacylglycerols (MGDG), digalactosyldiacylglycerols (DGDG) and sulfoquinovosyldiacylglycerols (SQDG) are major lipids in vegetable food. Their digestion and absorption are unknown. This study examines the hydrolysis of galactolipids in vitro with human duodenal contents, pancreatic juice, and purified human pancreatic lipases. Galactolipids were incubated with human duodenal contents, pancreatic juice, pure pancreatic carboxyl ester lipase (CEL), and colipase-dependent lipase with colipase (Lip-Col). Hydrolysis was estimated as release of free fatty acids and by the use of [3H]galactose or [3H]fatty acid-labeled DGDG. Pancreatic juice and duodenal contents hydrolyzed DGDG to fatty acids, digalactosylmonoacylglycerol (DGMG) and water-soluble galactose-containing compounds. The hydrolysis of DGDG was bile salt-dependent and had a pH optimum at 6.5-7.5. Human pancreatic juice released fatty acids from MGDG, DGDG, and SQDG. Purified CEL hydrolyzed all three substrates; the hydrolysis rate was MGDG > SQDG > DGDG. Pure Lip-Col had activity toward MGDG but had little activity against DGDG. Separation of pancreatic juice by Sephadex G100 gel filtration chromatography revealed two peaks with galactolipase activity that coincided with CEL (molecular mass 100 kD) and lipase (molecular mass 50 kD) peaks. In contrast to pure Lip-Col enzymes of the latter peak were as active against DGDG as against MGDG. Thus, DGDG is hydrolyzed both by CEL and by a pancreatic enzyme(s) with a molecular mass of 40-50 kD to fatty acids and lyso DGDG. MGDG, DGDG, and SQDG are all hydrolyzed by human pancreatic juice. Pure CEL hydrolyzed all three substrates.