来自鱼腥蓝细菌的氧化型黄素氧还蛋白的主链和侧链动力学

Main chain and side chain dynamics of oxidized flavodoxin from Cyanobacterium anabaena.

作者信息

Liu W, Flynn P F, Fuentes E J, Kranz J K, McCormick M, Wand A J

机构信息

The Johnson Research Foundation and Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.

出版信息

Biochemistry. 2001 Dec 11;40(49):14744-53. doi: 10.1021/bi011073d.

DOI:10.1021/bi011073d

PMID:11732893

Abstract

Oxidized flavodoxin from Cyanobacterium anabaena PCC 7119 is used as a model system to investigate the fast internal dynamics of a flavin-bearing protein. Virtually complete backbone and side chain resonance NMR assignments of an oxidized flavodoxin point mutant (C55A) have been determined. Backbone and side chain dynamics in flavodoxin (C55A) were investigated using (15)N amide and deuterium methyl NMR relaxation methods. The squared generalized order parameters (S(NH)(2)) for backbone amide N-H bonds are found to be uniformly high (<S(NH)(2)> approximately 0.923 over 109 residues in regular secondary structure), indicating considerable restriction of motion in the backbone of the protein. In contrast, methyl-bearing side chains are considerably heterogeneous in their amplitude of motion, as indicated by obtained symmetry axis squared generalized order parameters (S(axis)(2)). However, in comparison to nonprosthetic group-bearing proteins studied with these NMR relaxation methods, the side chains of oxidized flavodoxin are unusually rigid.

摘要

来自鱼腥藻PCC 7119的氧化型黄素氧还蛋白被用作研究含黄素蛋白快速内部动力学的模型系统。已确定氧化型黄素氧还蛋白点突变体（C55A）几乎完整的主链和侧链共振NMR归属。使用（15）N酰胺和氘代甲基NMR弛豫方法研究了黄素氧还蛋白（C55A）中的主链和侧链动力学。发现主链酰胺N-H键的平方广义序参数（S(NH)(2)）普遍较高（在规则二级结构中的109个残基上<S(NH)(2)>约为0.923），表明蛋白质主链中的运动受到相当大的限制。相比之下，如所获得的对称轴平方广义序参数（S(axis)(2)）所示，含甲基的侧链在运动幅度上存在相当大的异质性。然而，与用这些NMR弛豫方法研究的不含辅基的蛋白质相比，氧化型黄素氧还蛋白的侧链异常刚性。