Synthetic peptide models for the redox-active disulfide loop of glutaredoxin. Conformational studies.
Synthetic peptide models for the redox-active disulfide loop of glutaredoxin. Conformational studies.
复制标题
谷氧还蛋白氧化还原活性二硫键环的合成肽模型。
DOI：
10.1021/bi00407a032
复制
发表时间：
1988
期刊：
影响因子：
2.9
通讯作者：
P. Balaram
中科院分区：
文献类型：
--
作者：
R. Kishore;S. Raghothama;P. Balaram
两个环肽二硫化物(序列：见正文)。(X=L-酪氨酸或L-苯丙氨酸)已被合成作为谷氧还蛋白的14元氧化还原活性二硫键的模型。在270 MHz的氯仿溶液中的1H核磁共振研究建立了两个肽中Pro-X片段的I型β转角构象，该构象由Cys(1)CO和Cys(4)NH基团之间的4-1氢键稳定。核Overhauser效应确定了X=Phe多肽中的芳香环定位于中心多肽单元之上。在二甲基亚砜溶液中，观察到两种多肽在核磁共振时间尺度上缓慢交换的两种构象物种。这些被归类为类型I和类型II的β-转角结构，角残基为-Pro-Tyr(Phe)-。结构归属是基于与具有Pro-X间隔区的14元环胱氨酸肽模型的核磁共振参数的关联。基于-S-S-n-omega*转变的圆二色谱研究表明，随着溶剂极性的改变，二硫键的结构发生了变化，建立了这些体系中肽主链和二硫键之间的构象耦合。
Two cyclic peptide disulfides (Sequence: see text). (X = L-Tyr or L-Phe) have been synthesized as models for the 14-membered redox-active disulfide loop of glutaredoxin. 1H NMR studies at 270 MHz in chloroform solutions establish a type I beta-turn conformation for the Pro-X segment in both peptides, stabilized by a 4----1 hydrogen bond between the Cys(1) CO and Cys(4) NH groups. Nuclear Overhauser effects establish that the aromatic ring in the X = Phe peptide is oriented over the central peptide unit. In dimethyl sulfoxide solutions two conformational species are observed in slow exchange on the NMR time scale, for both peptides. These are assigned to type I and type II beta-turn structures with -Pro-Tyr(Phe)- as the corner residues. The structural assignments are based on correlation of NMR parameters with model 14-membered cyclic cystine peptides with Pro-X spacers. Circular dichroism studies based on the -S-S- n-omega* transition suggest a structural change in the disulfide bridge with changing solvent polarity, establishing conformational coupling between the peptide backbone and the disulfide linkage in these systems.