NMR studies of structure, hydrogen exchange, and main-chain dynamics in a disrupted-core mutant of thioredoxin.
NMR studies of structure, hydrogen exchange, and main-chain dynamics in a disrupted-core mutant of thioredoxin.
复制标题
硫氧还蛋白核心突变体的结构、氢交换和主链动力学的核磁共振研究。
DOI：
10.1002/pro.5560051218
复制
发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Spicer,LD
中科院分区：
文献类型：
--
作者：
DeLorimier,R;Hellinga,HW;Spicer,LD
Core‐packing mutants of proteins often approach molten globule states, and hence may have attributes of folding intermediates. We have studied a core‐packing mutant of thioredoxin, L78K, in which a leucine residue is substituted by lysine, using15N heteronuclear two‐ and three‐dimensional NMR. Chemical shift differences between the mutant and wild‐type main‐chain resonances reveal that structural changes caused by the mutation are localized within 12 Å of the altered side chain. The majority of resonances are unchanged, as are many1H‐1H NOEs indicative of the main‐chain fold, suggesting that the structure of L78K is largely similar to wild type. Hydrogen exchange studies reveal that residues comprising the central β‐sheet of both mutant and wild‐type proteins constitute a local unfolding unit, but with the unfolding/folding equilibrium approximately 12 times larger in L78K. The dynamics of main‐chain NH bonds in L78K were studied by15N spin relaxation and compared with a previous study of wild type. Order parameters for angular motion of NH bonds in the mutant are on average lower than in wild type, suggesting greater spatial freedom on a rapid time scale, but may also be related to different rotational correlation times in the two proteins. There is also evidence of greater conformational exchange in the mutant. Differences between mutant and wild type in hydrogen exchange and main‐chain dynamics are not confined to the vicinity of the mutation. We infer that mispacking of the protein core in one location affects local dynamics and stability throughout.
