精致的水晶的结构从金黄色葡萄球菌PC1 beta-lactamase 2.0决议。
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赫兹伯格O
精致的水晶的结构从金黄色葡萄球菌PC1 beta-lactamase 2.0决议。
J杂志。1991年2月20日,217(4):701 - 19所示。
- PubMed ID
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2005620 (在PubMed]
- 文摘
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类的晶体结构从金黄色葡萄球菌beta-lactamase PC1分辨率2.0一直在改进。由此产生的晶体R因子(R =σh平行的Fo [-] Fc平行/σh (Fo), (Fo)和(Fc)观察到的振幅和计算结构因素,分别),0.163 17547年反思我大于或等于2σ(I)在8.0到2.0决议范围内。分子由两个密切相关的领域。一个域是由一个five-stranded反平行的β褶板有三个螺旋填料的表。第二个域主要由螺旋形成包对的第二面单。活性位点位于两个域之间的界面,和许多残留的形式保存在所有已知的A类beta-lactamases序列。类似于丝氨酸蛋白酶,催化oxyanion洞有牵连。它是由两个主链的氮原子,催化seryl残渣,Ser70, Gln237 beta-strand主要β褶板边缘。Ser70交互与另一个守恒seryl残渣,Ser130,位于两个铵组之间的功能重要的赖氨酸残基,Lys73 Lys234。这种复杂的交互点第二个seryl残渣的可能的催化作用。 Another key catalytic residue is Glu166. There are several unusual structural features associated with the active site. (1) A cis peptide bond has been identified between the catalytic Glu166 and Ile167. (2) Ala69 and Leu220 have strained phi, psi dihedral angles making close contacts that restrict the conformation of the active site beta-strand involved in the formation of the oxyanion hole. (3) A buried aspartate residue, the conserved Asp233, is located next to the active site Lys234. It is interacting with another buried aspartyl residue, Asp246. An internal solvent molecule is also involved, but the rest of its interactions with the protein indicate it is not a cation. (4) Another conserved aspartyl residue that is desolvated is Asp131, adjacent to Ser130. Its charge is stabilized by interactions with four main-chain nitrogen atoms. (5) An internal cavity underneath the active site depression is filled with six solvent molecules. This, and an adjacent cavity occupied by three solvent molecules partially separate the omega-loop associated with the active site from the rest of the protein.(ABSTRACT TRUNCATED AT 250 WORDS)