The interaction of concanavalin A with methyl α-D-glucopyranoside
The interaction of concanavalin A with methyl α-D-glucopyranoside
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刀豆球蛋白 A 与甲基 α-D-吡喃葡萄糖苷的相互作用
DOI：
10.1016/0304-4165(68)90063-9
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发表时间：
1968
期刊：
影响因子：
--
通讯作者：
A. Levitki
中科院分区：
文献类型：
--
作者：
J. Yariv;A. Kalb;A. Levitki
伴刀豆球蛋白A是多年前从刀豆中分离得到的一种糖结合蛋白。伴刀豆球蛋白A在其结合β 2、β 3的pH范围内不是均质分子种类。甲基~-I~-吡喃葡萄糖苷等小分子糖的结合参数可能为该蛋白的理化性质提供依据。实际上，单个结合常数和当量描述了葡糖苷与伴刀豆球蛋白A的结合。结合的糖，我们发现，取决于二价金属含量的蛋白质。金属的去除破坏了糖的结合位点。蛋白质分离自刀豆粉（Sigma Chemical Co.，密苏里州圣路易斯）通过如4所述的两次结晶。卫星。将含有24 mg/ml蛋白质并将被称为储备溶液的NaCl滤液在室内保存几周而不变质。天然蛋白质是适当稀释的储备溶液，并在低温下对缓冲溶液进行几次透析。如所述5制备部分脱金属的蛋白质，通过在HCl中制备oIM蛋白质，并首先对无金属的水透析，然后对无金属的缓冲液透析。然而，蛋白质的去金属化不能完全重现，不同批次的金属含量不同（表I）。
Concanavalin A, a saccharide-binding protein from Jack bean was isolated by crystallization many years ago 1. Concanavalin A is not a homogeneous molecular species in the pH range where it binds saccharides 2, 3. It seemed possible that binding parameters for a small saccharide like methyl~-I~-glucopyranoside could furnish a physicochemical characterization of this protein. Indeed a single binding constant and an equivalent weight describe the binding of the glucoside by concanavalin A. Binding of the saccharide, we find, depends on divalent metal content of the protein. Removal of metal destroys the binding sites for the saccharide. The protein was isolated from Jack bean meal (Sigma Chemical Co., St. Louis, Mo.) by two crystallizations as described 4. The satd. NaC1 filtrate, which contained 24 mg/ml protein and will be referred to as stock solution, was kept in the room for a few weeks without deterioration. Native protein is stock solution appropriately diluted and dialyzed against a few changes of a buffer solution in the cold. Partially de-metallized protein was prepared as described 5 by making the protein oI M in HC1 and dialyzing first against metal-free water and then against metal-free buffer. De-metallization of protein was, however, not exactly reproducible and different batches varied in their metal content (Table I).