Kim Junghwa, Robinson Anne Skaja
Department of Chemical Engineering, University of Delaware, Newark 19716, USA.
Protein Sci. 2006 Jul;15(7):1791-3. doi: 10.1110/ps.062197206. Epub 2006 Jun 2.
Each chain of the native trimeric P22 tailspike protein has eight cysteines that are reduced and buried in its hydrophobic core. However, disulfide bonds have been observed in the folding pathway and they are believed to play a critical role in the registration of the three chains. Interestingly, in the presence of sodium dodecyl sulfate (SDS) only monomeric chains, rather than disulfide-linked oligomers, have been observed from a mixture of folding intermediates. Here we show that when the oligomeric folding intermediates were separated from the monomer by native gel electrophoresis, the reduction of intermolecular disulfide bonds did not occur in the subsequent second-dimension SDS-gel electrophoresis. This result suggests that when tailspike monomer is present in free solution with SDS, the partially unfolded tailspike monomer can facilitate the reduction of disulfide bonds in the tailspike oligomers.
天然三聚体P22尾刺蛋白的每条链都有8个半胱氨酸，这些半胱氨酸被还原并埋藏在其疏水核心中。然而，在折叠途径中观察到了二硫键，并且它们被认为在三条链的对齐中起关键作用。有趣的是，在十二烷基硫酸钠（SDS）存在的情况下，从折叠中间体混合物中仅观察到单体链，而不是二硫键连接的寡聚体。在这里我们表明，当通过天然凝胶电泳将寡聚折叠中间体与单体分离时，在随后的二维SDS凝胶电泳中分子间二硫键并未发生还原。该结果表明，当尾刺单体与SDS存在于游离溶液中时，部分展开的尾刺单体可以促进尾刺寡聚体中二硫键的还原。
