Crystal structure of endo-beta-N-acetylglucosaminidase F1, an alpha/beta-barrel enzyme adapted for a complex substrate.
Crystal structure of endo-beta-N-acetylglucosaminidase F1, an alpha/beta-barrel enzyme adapted for a complex substrate.
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内切-β-N-乙酰氨基葡萄糖苷酶 F1 的晶体结构，这是一种适用于复杂底物的 α/β-桶酶。
DOI：
10.1021/bi00251a005
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发表时间：
1994
期刊：
影响因子：
2.9
通讯作者：
Tarentino,AL
中科院分区：
文献类型：
--
作者：
VanRoey,P;Rao,V;PlummerJr,TH;Tarentino,AL
修订稿于 1994 年 8 月 22 日收到® 摘要：Endo-/3-V-乙酰氨基葡萄糖苷酶 Fi (Endo Fi) 是一种糖苷内切酶，由脑膜脓毒黄杆菌分泌，可在第一个/V-乙酰氨基葡萄糖残基后裂解天冬酰胺连接的寡糖。该酶对高甘露糖寡糖链具有选择性。 Endo Fi 的晶体结构已在 2.0-A 分辨率下测定。分子折叠由高度不规则的a//3-桶组成，这是一种常见的基序，由/3-链/环/a-螺旋单元的环状8倍重复组成，中心有八链平行/3-桶。 Endo Fi 缺少两个 α 螺旋，即单元 5 和单元 6 的单元。相反，/3 链 5 和 6 之后的连接由一个短转组成，后面是一个延伸构象的部分，该部分取代了螺旋和分子底部的一个长环。 3 链 5 和 6 之后的分子顶部不存在任何偏移，导致桶边缘出现明显凹陷。该凹陷形成浅裂缝的一端，该裂缝穿过分子表面，越过/3-桶的核心到达单元1和2的环之间的区域。活性位点残基Asp 130和Glul32位于/3-链4的羧基端并延伸到该裂缝中。这些残基被几个酪氨酸残基包围。由环1和2形成的裂口区域排列有极性残基，主要是天冬酰胺。后一个区域被认为负责寡糖的结合和识别，而底物的蛋白质部分将位于分子外部，但邻近环 5 和 6 的区域。该区域中缺少 α 螺旋导致更窄的桶形边缘具有更适应性的表面，这被认为对于促进与许多不同糖蛋白的相互作用很重要 Endo-/3-/V-乙酰氨基葡萄糖苷酶 Fi (Endo Fi) 1 是由脑膜败血黄杆菌分泌的三种糖苷内切酶之一（Plummer & Tarentino，1991；Trimble & Tarent-tino，1991）。这些酶水解天冬酰胺连接的寡糖的 A.iV'-二乙酰壳二糖核心的两个 JV-乙酰葡糖胺残基 (GlcNAc) 之间的 3-d-(1-4) 键。
Revised Manuscript Received August 22, 1994® abstract: Endo-/3-V-acetylglucosaminidase Fi (Endo Fi) is an endoglycosidase, secreted by Flavobacterium meningosepticum, that cleaves asparagine-linked oligosaccharides after the first/V-acetylglucosamine residue. The enzyme is selective for high-mannose oligosaccharide chains. The crystal structure of Endo Fi has beendetermined at 2.0-A resolution. The molecular fold consists of a highly irregular a//3-barrel, a commonly observed motif consisting of a cyclic 8-fold repeat of/3-strand/loop/a-helix units with an eight-stranded parallel/3-barrel at the center. Endo Fi lackstwo of the a-helices, those of units 5 and 6. Instead, the links after/3-strands 5 and 6 consist of a short turn followed by a section in an extended conformation thatreplaces the helix and a long loop at the bottom of the molecule. The absence of any excursion on top of the molecule following/3-strands 5 and 6 results in a pronounced depression in the rim of the barrel. This depression forms one end of a shallow cleft that runs across the surface of the molecule, over the core of the/3-barrel to the area between the loops of units 1 and 2. The active site residues, Asp 130 and Glul32, are located at the carboxyl end of/3-strand 4 and extend into this cleft. These residues are surrounded by several tyrosine residues. The cleft area formed by loops 1 and 2 is lined with polar residues, mainly asparagines. Thelatter area is thought to be responsible for oligosaccharide binding and recognition while the protein moiety of the substrate would be located outside the molecule but adjacent tothe area of loops 5 and 6. The absence of the a-helices in this area results in a narrower barrel rim with a more adaptable surface, which is thought to be important to facilitate interaction with many different glycoprotein substrates.Endo-/3-/V-acetylglucosaminidase Fi (Endo Fi) 1 is one of three endoglycosidases secreted byFlavobacterium meningosepticum (Plummer & Tarentino, 1991; Trimble & Taren-tino, 1991). These enzymes hydrolyze the/3-d-(1—4) bond between the two JV-acetylglucosamine residues (GlcNAc) of the A. iV'-diacetylchitobiose core of asparagine-linked oli-