摘要/Abstract
摘要： 目的·研究葡萄糖-6-磷酸脱氢酶（glucose-6-phosphate dehydrogenase，G6PD）基因突变对酶蛋白结构及功能的影响，了解G6PD突变与酶学结构、功能的关系。方法·回顾性分析2014—2017年上海市儿童医院205 103例新生儿G6PD缺乏症筛查记录，Wilcoxon 检验分析酶活性与突变基因类型之间的关系。采用Psipred、SOPMA、JPred4预测蛋白的二级结构，SWISS-MODEL 预测氨基酸链空间结构，Mupro、SDM、CUPSAT、mSCM、DUET、Dynamut预测蛋白突变前后稳定性变化，PROVEAN预测对蛋白功能的影响，PyMOL 和LigPlot+修饰蛋白空间结构预测图。结果·230例样本酶活性检测阳性，对其中121例进行基因检测，共检出8种突变，除c.95A>G、c.1376G>T、c.1388G>A 3种常见突变，c.1024C>T也表现出高发生率。4种突变均导致蛋白结构改变，稳定性降低，对功能有不良影响；此外，c.1388G>A突变导致其远离甘油配体结合区。结论·4种突变均通过改变蛋白结构进而降低蛋白的稳定性，其中c.1388G>A突变还会影响蛋白与底物的结合能力。
关键词: 葡萄糖-6-磷酸脱氢酶(G6PD)缺乏症, 基因突变, 酶活性, 酶蛋白结构, 蛋白稳定性
Abstract:
Objective · To analyze the effect of glucose-6-phosphate dehydrogenase (G6PD) gene mutations on the structure and function of enzymes. Methods · A retrospective analysis of G6PD screening records of 205 103 neonates collected in the Shanghai Children's Hospital from 2014 to 2017 was performed. Wilcoxon test was used to analyze the enzyme activity and mutant genes. The software tools Psipred, SOPMA, and JPred4 were used to predict the secondary structure of the protein, and the 3D structure of G6PD was predicted based on the amino acid chain by SWISS-MODEL and modified by PyMOL and LigPlot+. Six different analysis software programs, including Mupro, SDM, CUPSAT, mSCM, DUET, and Dynamut, were utilized to compare protein stability of the wild-type with the mutant forms. PROVEAN was used to analyze the effect of amino acid changes on the enzyme. Results · Two hundred and thirty samples were positive for enzyme deficiency, of which 121 positive samples were genetically tested and eight mutations were identified. Three common mutations c.95A>G, c.1376G>T, and c.1388G>A were present, and c.1024C>T mutation was identified in 14 samples. These four mutations induced a change in protein structure, reduced protein stability, and had adverse effects on function. In addition, c.1388G was adjacent to the glycerol ligand binding region in the wild type structure, whereas the c.1388G>A mutation caused this residue further away from it. Conclusion · Four nonsynonymous mutations (c.95A>G, c.1376G>T, c.1388G>A and c.1024C>T) reduce the stability of the G6PD enzyme by changing the structure of the protein, in which the c.1388G>A mutation also affects the binding ability of the protein to the substrate.
Key words: glucose-6-phosphate dehydrogenase (G6PD) deficiency, gene mutation, enzyme activity, protein structure, protein stability
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