Structural fluctuations of protein complexes measured by combination of protein engineering and solvent quenching meshod

本项目采用dmso淬灭H/D交换法研究大肠杆菌伴侣蛋白GroEL/ES体系的结构波动。对于GroES的H/D交换实验，我们成功地确定了GroES中94个酰胺质子中33个酰胺质子的交换速率。对于剩下的61个酰胺质子，我们已经确定了交换率的下限。我们发现只有10个酰胺质子的保护系数大于10的6次方。这一结果表明，自由GroES在很大程度上是高度灵活的。通过对GroEL/ES体系底物α -乳清蛋白n端突变体的晶体结构分析，我们发现n端残基的氢键对其稳定性至关重要。

In this project, we have been studying the structural fluctuations of E. coli chaperonin GroEL/ES system by using DMSO-quenched H/D exchange methods. For GroES H/D exchange experiments, we have successfully determined the exchange rates for 33 amide protons out of 94 amide protons in GroES. For the remaining 61 amide protons, we have determined the lower limit of the exchange rates. We found that only 10 amide protons have a protection factor larger than 10 to the power 6th. This result indicates that the free GroES is highly flexible in significant portions. From crystal structure analysis of N-terminal mutants of alpha-lactalbumin, a substrate protein of GroEL/ES system, we found the hydrogen bonding of the N-terminal residue is important for its stability.