细化人体基本结构的纤维母细胞生长因子在1.6的分辨率和分析推测硒酸肝素结合位点的替换。
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埃里克森AE, Cousens LS,马修斯BW
细化人体基本结构的纤维母细胞生长因子在1.6的分辨率和分析推测硒酸肝素结合位点的替换。
蛋白质科学。1993年8月,2 (8):1274 - 84。
- PubMed ID
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7691311 (在PubMed]
- 文摘
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人类基本的三维结构纤维母细胞生长因子精制结晶剩余的16.1%在1.6一项决议。结构Kunitz-type褶皱,由12个反平行的beta-strands,其中6 beta-barrel。一个绑定硫酸盐离子被确认在这个模型中,氢连着Asn 27的侧链,Arg 120,赖氨酸125。Arg的侧链120有两个构象,这两个许可证氢键硫酸。这种硫酸结合位点被认为是肝素结合位点(埃里克森,A.E.、Cousens L.S.韦弗,L.H.、& Matthews B.W.,1991年,Proc。国家的。学会科学。美国88年、3441 - 3445)。两个beta-mercaptoethanol (BME)分子也包含在模型中,每个年代伽马原子形成二硫键的半胱氨酸69年和92年半胱氨酸,分别。 The side chain of Cys 92 has two conformations of which only one can bind BME. Therefore the BME molecule is half occupied at this site. The locations of possible sulfate binding sites on the protein were examined by replacing the ammonium sulfate in the crystallization medium with ammonium selenate. Diffraction data were measured to 2.2 A resolution and the structure refined to an R-factor of 13.8%. The binding of the more electron-dense selenate ion was identified at two positions. One position was identical to the sulfate binding site identified previously. The second selenate binding site, which is of lower occupancy, is situated 5.6 A from the first. This ion is hydrogen bonded by the side chain of Lys 135 and Arg 120. Thus the side chain of Arg 120 binds two selenate ions simultaneously. It is suggested that the observed second selenate binding site should also be considered as a possible binding site for heparin, or that both selenate binding sites might simultaneously contribute to the binding of heparin.