Characteristics in digestion and absorption of protein in an artificial diet in the silkworm, Bombyx mori

家蚕人工饲料中蛋白质的消化吸收特性

• 批准号: 09660057
• 负责人: SUMIDA Motoyuki
• 金额: $ 1.98万
• 依托单位: Kyoto Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09660057/
• 关键词: Protein; Digestion and absorption; Artificial diet; Membrane-bound enzyme; Solubilization; Aminopeptidase; Peptide; Silkworm; 膜結合型; 中腸組織

To elucidate the physiological role of membrane-bound aminopeptidase of the larval midgut of the silkworm, Bombyx mori, especially in digestion and absorption of protein in an artificial diet, following three points were investigated. 1) longitudinal localization of enzyme in the midgut tissue, 2) Establishment of method of purification of the enzyme 3) Effect of protein content in an artificial diet on the enzyme activity.The results were as follows.1. Midgut tissue can be divided into three portions, namely, anterior, middle and posterior ones. Among them, the posterior portion was highest in activity per individual tissue basis, followed by the rest two portions with almost equal activities. This suggests that posterior portion plays a significant role in digestion and absorption of protein in the midgut.2. A purification method was established. It employs solubilization of enzyme from midgut membrane fraction using an enzyme, phosphatidylinositol specific phospholipase C, followed by column chromatographies using separationmedia of ion exchange, metal chelate, and gel filtration.3. The enzyme activity in the midgut of the silkworm larvae fed artificial diet containing protein of 6.4% and 13.2% in wet weight increased significantly compared to controls. This suggests that the enzyme is inducible upon feeding diet : with high content of protein.The present study investigated an enzyme which is supposedly involved in digestion and absorption of protein in this insect. Another completely different approach is possible and we have a plan to do it shortly. It is a study of products analysis of protein digestion in the midgut tissue, absorbed peptides. if any, in the midgut cells, and absorbed peptides, if any, in the haemolymph in this insect. By identification of peptides of digestion products, we speculate the aproteases and peptidases that were involved in digestion. Then we search for the enzymes.

为了阐明家蚕幼虫中肠膜结合氨基肽酶的生理作用，特别是在人工饲料中对蛋白质的消化和吸收，本文从三个方面进行了研究。1)酶在中肠组织中的纵向定位；2)酶纯化方法的建立；3)人工饲料中蛋白质含量对酶活性的影响。中肠组织可分为前、中、后三部分。其中，后部的每个组织的活性最高，其次是其余两个部分，活性几乎相等。这表明后部在中肠蛋白质的消化和吸收中起着重要的作用。建立了一种纯化方法。它使用磷脂酰肌醇特异性磷脂酶C从中肠膜部分中溶解酶，然后使用离子交换、金属螯合和凝胶过滤分离介质进行柱层析。饲喂蛋白质含量为6.4%和13.2%的人工饲料的家蚕幼虫中肠酶活性显著高于对照组。这表明这种酶在饲料中是可诱导的：蛋白质含量很高。本研究调查了一种被认为参与这种昆虫对蛋白质的消化和吸收的酶。另一种完全不同的方法是可能的，我们有一个计划很快就会这样做。它是对中肠组织中蛋白质消化产物分析的研究，吸收的多肽。如果有的话，在中肠细胞中，如果有的话，在这种昆虫的血淋巴中吸收肽。通过对消化产物中的多肽进行鉴定，推测与消化有关的非蛋白水解酶和肽酶。然后我们寻找酶。