Isolation and characterization from potato tubers of two polypeptide inhibitors of serine proteinases.
Isolation and characterization from potato tubers of two polypeptide inhibitors of serine proteinases.
复制标题
从马铃薯块茎中分离和鉴定两种丝氨酸蛋白酶多肽抑制剂。
DOI：
10.1016/0003-9861(82)90571-9
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发表时间：
1982
影响因子：
3.9
通讯作者：
G. Hass
中科院分区：
文献类型：
--
作者：
G. Pearce;L. Sy;C. Russell;C. Ryan;G. Hass
从Russet伯班克马铃薯块茎中分离到电泳均一性的两种多肽是胰腺丝氨酸蛋白酶的强效抑制剂。其中一种抑制剂称为多肽胰蛋白酶抑制剂，PTI，分子量为5100，抑制牛胰蛋白酶。该抑制剂不含甲硫氨酸、组氨酸和色氨酸，含有8个半胱氨酸残基作为4个二硫键。第二种抑制剂，多肽胰凝乳蛋白酶抑制剂II，PCI-II，具有5700的分子量，并强烈抑制胰凝乳蛋白酶。该抑制剂也不含甲硫氨酸和色氨酸，但它仅含有六个半胱氨酸作为三个二硫键。两种多肽均强烈抑制胰腺弹性蛋白酶。在免疫双扩散测定中，多肽胰蛋白酶抑制剂和多肽胰凝乳蛋白酶抑制剂II表现出高度的免疫同一性（a）彼此相同，（B）与多肽胰凝乳蛋白酶抑制剂相同（c）用抑制剂II，一种较大的抑制剂，（单体Mr ~ 12，000）胰蛋白酶和胰凝乳蛋白酶两者的抑制剂，其先前也已从马铃薯块茎中分离。现在从Russet伯班克马铃薯块茎中分离的四种多肽蛋白酶抑制剂累积抑制动物的所有五种主要肠消化内蛋白酶和外蛋白酶。这些抑制剂被认为是抗营养素，作为马铃薯块茎抵抗害虫攻击的天然化学防御机制的一部分而存在。
Two polypeptides, isolated to electrophoretic homogeneity from Russet Burbank potato tubers, are powerful inhibitors of pancreatic serine proteinases. One of the inhibitors, called polypeptide trypsin inhibitor, PTI, has a molecular weight of 5100, and inhibits bovine trypsin. The inhibitor is devoid of methionine, histidine, and tryptophan and contains eight half-cystine residues as four disulfide bridges. The second inhibitor, polypeptide chymotrypsin inhibitor II, PCI-II, has a molecular weight of 5700 and powerfully inhibits chymotrypsin. This inhibitor is also devoid of methionine and tryptophan but it contains only six of half-cystines as three disulflde bonds. Both polypeptides strongly inhibit pancreatic elastase. In immunological double diffusion assays, polypeptide trypsin inhibitor and polypeptide chymotrypsin inhibitor II exhibit a high degree of immunological identity (a) with each other, (b) with a polypeptide chymotrypsin inhibitor (PCI-I,Mr5400) previously isolated from potato tubers, and (c) with inhibitor II, a larger (monomerMr~ 12,000) inhibitor of both trypsin and chymotrypsin which has also been previously isolated from potato tubers. The four polypeptide proteinase inhibitors now isolated from Russet Burbank potato tubers cumulatively inhibit all five major intestinal digestive endo- and exoproteinases of animals. The inhibitors are thought to be antinutrients that are present as part of the natural chemical defense mechanisms of potato tubers against attacking pests.