大麦粉中的乳糖水解β-糖苷酶

Lactose-hydrolyzing beta-glycosidases of barley meal.

作者信息

Simos G, Georgatsos J G

机构信息

Laboratory of Biochemistry, School of Chemistry, University of Thessaloniki, Greece.

出版信息

Biochim Biophys Acta. 1988 Oct 13;967(1):17-24. doi: 10.1016/0304-4165(88)90183-3.

DOI:10.1016/0304-4165(88)90183-3

PMID:3139043

Abstract

A beta-glucosidase and a beta-galactosidase were purified to homogeneity from barley meal. The beta-glucosidase is a single basic polypeptide (pI greater than 8.5) with an Mr of 53,000 acting optimally at pH 4.5-5.0. The beta-galactosidase is composed of two subunits with an Mr of 42,000 and 33,000, respectively, and is acidic in nature (pI less than 5.7). Both enzymes are able to hydrolyze lactose with Michaelis constants lower than the concentration of this sugar in milk whey. Consequently, barley seems to be an inexpensive source of lactose-splitting enzymes.

摘要

从大麦粉中纯化出了一种β-葡萄糖苷酶和一种β-半乳糖苷酶，使其达到了均一性。β-葡萄糖苷酶是一种单一的碱性多肽（pI大于8.5），相对分子质量为53,000，在pH 4.5 - 5.0时活性最佳。β-半乳糖苷酶由两个亚基组成，相对分子质量分别为42,000和33,000，本质上呈酸性（pI小于5.7）。这两种酶都能够水解乳糖，其米氏常数低于乳清中这种糖的浓度。因此，大麦似乎是一种廉价的乳糖分解酶来源。