半胱氨酸蛋白酶和羧肽酶在荞麦种子贮藏蛋白降解中的作用。
The role of cysteine proteinase and carboxypeptidase in the breakdown of storage proteins in buckwheat seeds.
机构信息
A.N. Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, 119899, Moscow, USSR.
出版信息
Planta. 1989 Oct;179(3):316-22. doi: 10.1007/BF00391076.
Two proteolytic enzymes, a cysteine proteinase and a carboxypeptidase, responsible for breakdown of the main storage protein, 13S globulin, were purified from buckwheat seedlings (Fagopyrum esculentum Moench) by (NH4)2SO4 fractionation, gel-filtration on Sephadex G-150, ionexchange chromatography on DEAE-Toyopearl 650 M and chromatofocusing. The cysteine proteinase was purified 74-fold. It has a pH optimum of 5.5, a pI of 4.5 and an apparent molecular mass (Mr) of 71000. The carboxypeptidase was purified 128-fold. It has a pH optimum of 5.3, a pI of 5.8 and a Mr of 78500. Cysteine proteinase hydrolyzed the modified 13S globulin only if the reaction products were eliminated from the incubation mixture by dialysis. Storage protein degradation by the proteinase increased in the presence of carboxypeptidase. We suggest that the two enzymes complete the digestion of 13S globulin after its preliminary hydrolysis by the earlier described enzyme, metalloproteinase, present in dry buckwheat seeds.
两种蛋白水解酶，一种半胱氨酸蛋白酶和一种羧肽酶，负责分解主要的贮藏蛋白 13S 球蛋白，从小麦（Fagopyrum esculentum Moench）幼苗中通过（NH4）2SO4 分级沉淀、Sephadex G-150 凝胶过滤、DEAE-Toyopearl 650 M 离子交换色谱和等电聚焦进行纯化。半胱氨酸蛋白酶得到了 74 倍的纯化。它的 pH 最适值为 5.5，等电点为 4.5，表观分子量（Mr）为 71000。羧肽酶得到了 128 倍的纯化。它的 pH 最适值为 5.3，等电点为 5.8，Mr 为 78500。只有在将反应产物从孵育混合物中通过透析去除的情况下，半胱氨酸蛋白酶才能水解修饰后的 13S 球蛋白。在羧肽酶存在的情况下，蛋白水解酶促进贮藏蛋白的降解。我们认为，这两种酶在先前描述的存在于干荞麦种子中的金属蛋白酶对半胱氨酸蛋白酶水解的初步水解之后，完成了 13S 球蛋白的消化。
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