基于氨基酸序列和圆二色光谱法解析大肠杆菌6-磷酸葡糖胺脱氨酶的二级结构

Secondary structure of Escherichia coli glucosamine-6-phosphate deaminase from amino acid sequence and circular dichroism spectroscopy.

作者信息

Altamirano M M, Plumbridge J A, Hernández-Arana A, Calcagno M

机构信息

Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City.

出版信息

Biochim Biophys Acta. 1991 Jan 29;1076(2):266-72. doi: 10.1016/0167-4838(91)90277-7.

DOI:10.1016/0167-4838(91)90277-7

PMID:1998726

Abstract

The secondary structure of the purified glucosamine-6-phosphate deaminase from Escherichia coli K12 was investigated by both circular dichroism (CD) spectroscopy and empirical prediction methods. The enzyme was obtained by allosteric-site affinity chromatography from an overproducing strain bearing a pUC18 plasmid carrying the structural gene for the enzyme. From CD analysis, 34% of alpha-helix, 9% of parallel beta-sheet, 11% of antiparallel beta-sheet, 15% turns and 35% of non-repetitive structures, were estimated. A joint prediction scheme, combining six prediction methods with defined rules using several physicochemical indices, gave the following values: alpha-helix, 37%; beta-sheet, 22%; turns, 18% and coil, 23%. The structure predicted showed also a considerable degree of alternacy of alpha and beta structures; 64% of helices are amphipathic and 90% of beta-sheets are hydrophobic. Overall, the data suggest that deaminase has as dominant motif, an alpha/beta structure.

摘要

通过圆二色光谱法（CD）和经验预测方法，对来自大肠杆菌K12的纯化的6-磷酸氨基葡萄糖脱氨酶的二级结构进行了研究。该酶是通过变构位点亲和色谱法从携带该酶结构基因的pUC18质粒的过量生产菌株中获得的。通过CD分析，估计α-螺旋占34%，平行β-折叠占9%，反平行β-折叠占11%，转角占15%，非重复结构占35%。一种联合预测方案，结合六种预测方法并使用几个物理化学指标制定规则，得出以下值：α-螺旋占37%；β-折叠占22%；转角占18%，卷曲占23%。预测的结构还显示出α和β结构有相当程度的交替；64%的螺旋是两亲性的，90%的β-折叠是疏水性的。总体而言，数据表明脱氨酶具有α/β结构作为主要基序。