期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2003
卷号：100
期号：20
页码：11345-11349
DOI：10.1073/pnas.1635051100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Ribonucleases H from the thermophilic bacterium Thermus thermophilus and the mesophile Escherichia coli demonstrate a dramatic and surprising difference in their change in heat capacity upon unfolding ({Delta}Cp{degrees}). The lower {Delta}Cp{degrees} of the thermophilic protein directly contributes to its higher thermal denaturation temperature (Tm). We propose that this {Delta}Cp{degrees} difference originates from residual structure in the unfolded state of the thermophilic protein; we verify this hypothesis by using a mutagenic approach. Residual structure in the unfolded state may provide a mechanism for balancing a high Tm with the optimal thermodynamic stability for a protein's function. Structure in the unfolded state is shown to differentially affect the thermodynamic profiles of thermophilic and mesophilic proteins.
