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pepsin

消化

关键词消化 临床研究术语 消化不良

词汇介绍

拓展阅读

解析

pepsin 英 [ˈpepsɪn] 美 ['pepsɪn]

释义   n. 胃蛋白酶

例句   Ulcer is caused by the bacteria called Helicobacter pylori and by excessive internal secretions of gastric acid and pepsin. 溃疡是由细菌引起的称为幽门螺杆菌与胃酸分泌过多、胃蛋白酶的内部。


概述

胃蛋白酶(pepsin,Pep)属于天冬氨酸蛋白水解酶类,是胃消化蛋白水解酶,相对分子质量为 3.1×104~3.6×104,其前体是胃蛋白酶原,由胃黏膜主细胞所分泌,功能是将食物中的蛋白质分解为小的肽片段。主细胞分泌的是胃蛋白酶原,胃蛋白酶原经胃酸或者胃蛋白酶刺激后,形成胃蛋白酶。胃蛋白酶是胃内唯一的一种蛋白水解酶,其最适pH值为1~2。胃蛋白酶作用的主要部位是芳香族氨基酸,或酸性氨基酸的氨基所组成的肽链,具有消化蛋白质的能力。 正常值基础胃液胃蛋白酶分泌量为84.4±9.72m

Lipid protection by polyphenol-rich apple matrices is modulated by pH and pepsin in in vitro gastric digestion复制标题

富含多酚的苹果基质在体外胃消化中受pH和胃蛋白酶调节的脂质保护

发表时间:2019-07-17

影响因子:3.2

作者: Gaëtan Boléa

期刊:Food & Function

Lipid oxidation takes place in the gastric tract after the ingestion of a Western diet rich in ω-6 polyunsaturated fatty acids (PUFA) and red meat (heme iron). The incorporation of oxidation products such as 4-hydroxy-2-nonenal (4-HNE) into low-density lipoproteins is further correlated to endothelial dysfunction. Gastric postprandial stress could thus be reduced by antioxidant phytomicronutrients. The aim of this study was to investigate dietary lipid oxidation and its inhibition by apple polyphenols under different matrix forms (fresh fruit, puree, extract) under in vitro gastric digestion conditions. A deep insight was given into the two factors pH and pepsin governing the metmyoglobin-initiated lipid oxidation of sunflower oil-in-water emulsions simulating the physical state of dietary lipids. Our results first showed that pepsin accelerated lipid oxidation at pH 5 through the formation of a micro-metmyoglobin form likely displaying a higher accessibility to lipids. Spectroscopic studies further highlighted the formation of a reversible unfolded metmyoglobin form at pH 3 which was shown to be more pro-oxidant in the absence of pepsin. At nutritional levels, the three apple matrices inhibited less efficiently the accumulation of lipid-derived conjugated dienes and 4-HNE at pH 5 when pepsin was present whereas at pH 3 the opposite was true. High initial bioaccessibilities of monomeric phenolic compounds were evidenced for both puree (57–74%) and the phenolic extract (79–96%) compared to fresh apple (1–14%) supporting their greater antioxidant capacity. By contrast, the bioaccessibility of dimer B2 was low for all matrices suggesting non-covalent binding to apple pectins.

译文

摄入富含ω-6多不饱和脂肪酸(PUFA)和红肉(血红素铁)的西方饮食后,脂肪氧化发生在胃道中。氧化产物如4-羟基-2-壬烯醛(4-HNE)掺入低密度脂蛋白中还与内皮功能障碍有关。因此,可以通过抗氧化剂植物微量营养素减少胃餐后应激。这项研究的目的是研究在体外胃液消化条件下,膳食脂质氧化及其在不同基质形式(新鲜水果,果泥,提取物)下对苹果多酚的抑制作用。深入了解了两个因素,pH和胃蛋白酶控制着葵花红蛋白水乳液中肌红蛋白引发的脂质氧化,从而模拟了膳食脂质的物理状态。我们的结果首先表明,胃蛋白酶通过形成微肌红蛋白形式在pH 5时加速脂质氧化,这可能显示出对脂质的更高可及性。光谱研究进一步强调了在pH 3时可逆的未折叠的肌红蛋白形式的形成,在没有胃蛋白酶的情况下,该形式被证明具有更强的促氧化剂作用。在营养水平上,当存在胃蛋白酶时,这三种苹果基质在pH 5时抑制脂质衍生的共轭二烯和4-HNE积累的效率较低,而在pH 3时相反。与新鲜苹果(1-14%)相比,果泥(57-74%)和酚类提取物(79-96%)均具有较高的单体酚类化合物初始生物利用度,这证明了其具有更大的抗氧化能力。相比之下,对于所有基质,二聚体B2的生物可及性均较低,这表明与苹果果胶的非共价结合。