Effects of macromolecular crowding on glycoprotein processing enzymes
Effects of macromolecular crowding on glycoprotein processing enzymes
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DOI：
10.1021/ja077570k
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发表时间：
2008-02-13
影响因子：
15
通讯作者：
Ito, Yukishige
中科院分区：
文献类型：
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作者：
Totani, Kiichiro;Ihara, Yoshito;Ito, Yukishige
由于各种生物大分子的存在，细胞内环境高度拥挤。在这项研究中，我们估计了大分子拥挤条件下内质网葡萄糖苷酶II(G-II)的性质。含有牛血清白蛋白的拥挤环境极大地增强了第二修剪步骤(裂解2)，该步骤可使GLC(1)Man(9)GIcNAc(2)脱糖，但不能促进第一修剪步骤(裂解1)，该步骤可从GIC(2)Man(9)GIcNAc(2)中去除末端葡萄糖残基。核糖核酸酶A和高相对分子质量聚乙二醇20000也有类似的效果。圆二色谱分析表明，G-II通过构象变化增强了其裂解2活性。我们还研究了分子拥挤对其他N-连接的糖加工酶UDP-GLC：糖蛋白葡萄糖转移酶和1，2-α-甘露糖苷酶的影响。我们的结果表明，在拥挤条件下的葡聚糖加工动力学可能与在稀缓冲液中测得的有很大不同。
yIntracellular environments are highly crowded due to the presence of various biomacromolecules. In this study, we estimated the property of the endoplasmic reticulum glucosidase II (G-II) under macromolecular crowding conditions. A crowded milieu that contains bovine serum albumin greatly enhanced the second trimming step (cleavage 2), which deglucosylates Glc(1)Man(9)GIcNAc(2), but not the first trimming step (cleavage 1), which removes the terminal glucose residue from GIC(2)Man(9)GIcNAC(2). A similar effect was obtained with ribonuclease A and high molecular weight polyethylene glycol 20 000. An analysis of CD spectra suggested that G-II enhanced its cleavage 2 activity through conformational change. We also investigated the effects of molecular crowding on other N-linked glycan-processing enzymes, UDP-Glc: glycoprotein glucosyltransfe rase and 1,2-alpha-mannosidase. Our results indicate that the kinetics of glycan processing under crowded conditions may be quite different from those measured in dilute buffers.