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

在这个项目中，我们一直在研究E的结构波动。coli伴侣蛋白GroEL/ES系统。对于GroES H/D交换实验，我们已经成功地确定了GroES中94个酰胺质子中的33个酰胺质子的交换率。对于剩余的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个酰胺质子的保护因子大于10的6次方。该结果表明，自由GroES在显著部分中是高度柔性的。通过对GroEL/ES系统的底物蛋白α-乳白蛋白N端突变体的晶体结构分析，发现N端残基的氢键对其稳定性有重要影响。

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.