Liao D I, Kapadia G, Ahmed H, Vasta G R, Herzberg O
Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville 20850.
Proc Natl Acad Sci U S A. 1994 Feb 15;91(4):1428-32. doi: 10.1073/pnas.91.4.1428.
The crystal structure of a 14-kDa bovine spleen S-lectin complexed with the disaccharide N-acetyllactosamine at 1.9-A resolution reveals a surprising structural relationship to legume lectins, despite the lack of sequence homology. Two monomers associate to form an extended beta-sandwich, each with the same jelly roll topology typical of legume lectins but with dramatically trimmed loops and with different dimer association. Each monomer binds one N-acetyllactosamine molecule in a topologically and spatially different site than that of legume lectins. The carbohydrate-binding site provides an unprecedented paradigm for carbohydrate binding, with a unique network of salt bridges. The specificity for beta-galactose arises from intricate interactions that constrain the position of the O4 atom.
一个与二糖N-乙酰乳糖胺复合的14千道尔顿牛脾S-凝集素在1.9埃分辨率下的晶体结构揭示了它与豆科植物凝集素惊人的结构关系，尽管缺乏序列同源性。两个单体缔合形成一个延伸的β-折叠片层，每个单体都具有豆科植物凝集素典型的相同果冻卷拓扑结构，但环显著缩短且二聚体缔合方式不同。每个单体在拓扑和空间上与豆科植物凝集素不同的位点结合一个N-乙酰乳糖胺分子。碳水化合物结合位点提供了一个前所未有的碳水化合物结合模式，具有独特的盐桥网络。对β-半乳糖的特异性源于限制O4原子位置的复杂相互作用。
