Structural determinants of concanavalin A specificity for oligosaccharides.
Structural determinants of concanavalin A specificity for oligosaccharides.
复制标题
刀豆球蛋白 A 对寡糖的特异性的结构决定因素。
DOI：
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发表时间：
1979
影响因子：
4.8
通讯作者：
D. Fiete
中科院分区：
文献类型：
--
作者：
J. Baenziger;D. Fiete
碘化糖肽（50至200 × 103 cpm/pmol）已被用来检查影响与伴刀豆球蛋白A的糖结合位点的相互作用的结构决定因素的饱和曲线的Scatchard图分析。结合常数在4.5 × 10 ~（-6）M ~（-1）和25 × 10 ~（-6）M ~（-1）范围内的糖肽被伴刀豆球蛋白A-Sepharose保留，而结合常数在0.3 × 10 ~（-6）M ~（-1）和4.0 × 10 ~（-6）M ~（-1）范围内的糖肽不被伴刀豆球蛋白A-Sepharose保留。所有的糖肽检查有一个核心的结构：Mancul + 3[Manal --+ G]Manpl + 4GlcNAcj？l+ 4GlcNAc + Asn。2 α-连接的甘露糖残基的存在对于与糖结合位点的相互作用是必不可少的，其产生4.5 × 106 M-1或更大的缔合常数。在α-连接的甘露糖残基的C-2位存在取代基不会将缔合常数降低到低于4.5 × 106 M-1;然而，连续去除C-2位产生的分支上的外围糖导致核心结构的缔合常数逐渐增加至最大值20至23 × 106 M-1。与单独的核心糖相比，额外的α-连接的甘露糖残基不会导致缔合常数的显著增加。在cwl，6-连接的甘露糖上存在单个f11，4-连接的N-乙酰葡糖胺残基足以将缔合常数降低至3.3 × 106 M-1。如果cul，3-连接的甘露糖带有由C-2位产生的Gal@ --+ 4GlcNAcfil+组成的分支，则具有连接到b-连接的甘露糖的N-乙酰葡糖胺残基的糖肽显示2.0 × 106 Mm-1或更小的缔合常数。去除半乳糖导致缔合conStaXIt增加至5.0 × 106 M-1。
Iodinated glycopeptides (50 to 200 x lo3 cpm/pmol) have been utilized to examine the structural determinants affecting interaction with the saccharide binding site of concanavalin A by Scatchard plot analyses of saturation curves. Glycopeptides with association constants in the range of 4.5 X 10’ M-’ and 25 X 10’ Mm1 are retained by concanavalin A-Sepharose while glycopeptides with association constants in the range of 0.3 x lo6 M-’ and 4.0 X 10’ M-’ are not retained by concanavalin A-Sepharose. All of the glycopeptides examined have a core with the structure: Mancul + 3[Manal --+ G]Manpl + 4GlcNAcj?l+ 4GlcNAc + Asn. The presence of the 2 a-linked mannose residues is essential for interactions with the saccharide binding site that yield association constants of 4.5 X IO6 M-’ or greater. The presence of substituents at position C-2 of the a-linked mannose residues does not reduce the association constants below 4.5 x lo6 M-‘; however, sequential removal of peripheral sugars on branches arising from position C-2 results in a progressive increase in the association constants to a maximum of 20 to 23 X lo6 Mm1 for the core structure. Additional a-linked mannose residues do not result in a significant increase in the association constant as compared to the core sugars alone. The presence of a single fl1,4-linked N-acetylglucosamine residue on the cwl,6-linked mannose is sufficient to reduce the association constant to 3.3 x lo6 M-‘. Glycopeptides with an N-acetylglucosamine residue linked /31,4 to the b-linked mannose display an association constant of 2.0 X lo6 Mm1 or less if the cul,3-linked mannose bears a branch consisting of Gal@ --+ 4GlcNAcfil+ arising from position C-2. Removal of the galactose results in an increase of the association conStaXIt to 5.0 X lo6 M-‘.