Department of Physiological Chemistry, University of Veterinary Medicine Hannover, Hannover D-30559, Germany.
Nutrients. 2017 Oct 10;9(10):1106. doi: 10.3390/nu9101106.
In this study, we used a brush border membrane (BBM) preparation from human small intestine to analyze the proportion and the activity of major intestinal disaccharidases, including sucrase-isomaltase (SI), maltase-glucoamylase (MGAM) and lactase-phlorizin hydrolase (LPH). SI, MGAM and LPH respectively constituted 8.2%, 2.7% and 1.4% of total BBM protein. The activity of SI and LPH decreased threefold after purification from the brush border membrane, which highlights the effect of membrane microdomains on the functional capacity of these enzymes. All of the disaccharidases showed optimal activity at pH 6, over 50% residual activity between pH 5 to pH 7, and increasing activity with rising temperatures up to 45 °C, along with a stable functional structure. Therefore the enzymes can withstand mild intraluminal pH alterations with adequate function, and are able to increase their activity with elevated core body temperature. Our data provide a functional measure for characterization of intestinal disaccharidases under different physiological and pathological conditions.
在这项研究中，我们使用了来自人小肠的刷状缘膜（BBM）制剂来分析主要肠道二糖酶的比例和活性，包括蔗糖酶-异麦芽糖酶（SI）、麦芽糖酶-葡糖淀粉酶（MGAM）和乳糖酶-根皮苷水解酶（LPH）。SI、MGAM 和 LPH 分别占 BBM 总蛋白的 8.2%、2.7%和 1.4%。从刷状缘膜纯化后，SI 和 LPH 的活性降低了三倍，这突出了膜微区对这些酶功能能力的影响。所有二糖酶在 pH6 时表现出最佳活性，在 pH5 到 pH7 之间有超过 50%的残余活性，并且随着温度升高到 45°C 而活性增加，同时具有稳定的功能结构。因此，这些酶可以耐受适度的腔内 pH 变化，保持充分的功能，并且能够随着核心体温升高而增加其活性。我们的数据为不同生理和病理条件下肠道二糖酶的功能特征提供了一种功能度量。
