Sánchez A, Villanueva J R, Villa T G
J Gen Microbiol. 1982 Dec;128(12):3051-60. doi: 10.1099/00221287-128-12-3051.
Addition of tunicamycin to the culture medium of growing Saccharomyces cerevisiae protoplasts or cells resulted in the formation of a modified exo-1,3-beta-D-glucanase which was detectable in both extracellular and intracellular fractions. This modified enzyme had a lower molecular weight than the native form and did not bind to concanavalin A. The activation energy and Km values of both enzyme forms were identical. Antibodies raised against the native protein readily precipitated the exo-1,3-beta-D-glucanase produced after tunicamycin treatment. The latter enzyme was comparable, in terms of molecular size and lack of affinity for concanavalin A, to the beta-D-glucanase obtained by treatment of the native form with endoglycosidase H; both lacked the carbohydrate moiety present in the native enzyme. The exo-1,3-beta-D-glucanase obtained in the presence of the antibiotic was more sensitive to variations in temperature and pH than both endoglycosidase H-treated and non-treated enzymes. Our results suggest that the carbohydrate moiety, if not necessary for exo-1,3-beta-D-glucanase secretion, may play a role in the conformation of the protein and in stabilizing the enzymic activity.
在生长的酿酒酵母原生质体或细胞的培养基中添加衣霉素会导致形成一种修饰的外切-1,3-β-D-葡聚糖酶，该酶在细胞外和细胞内部分均能检测到。这种修饰后的酶分子量低于天然形式，且不与伴刀豆球蛋白A结合。两种酶形式的活化能和米氏常数相同。针对天然蛋白产生的抗体很容易沉淀衣霉素处理后产生的外切-1,3-β-D-葡聚糖酶。就分子大小和对伴刀豆球蛋白A缺乏亲和力而言，后一种酶与用内切糖苷酶H处理天然形式得到的β-D-葡聚糖酶相当；两者都缺乏天然酶中存在的碳水化合物部分。在抗生素存在下获得的外切-1,3-β-D-葡聚糖酶比内切糖苷酶H处理的酶和未处理的酶对温度和pH变化更敏感。我们的结果表明，碳水化合物部分，如果对外切-1,3-β-D-葡聚糖酶的分泌不是必需的，可能在蛋白质的构象和稳定酶活性方面发挥作用。
