A Cα−H···O Hydrogen Bond in a Membrane Protein Is Not Stabilizing
| Autor: | David Grosfeld, Sarah Yohannan, Duan Yang, Salem Faham, and Aaron K. Chamberlain, James U. Bowie |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | Journal of the American Chemical Society. 126:2284-2285 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja0317574 |
| Popis: | Hydrogen bonds involving a carbon donor are very common in protein structures, and energy calculations suggest that Cα−H···O hydrogen bonds could be about one-half the strength of traditional hydrogen bonds. It has therefore been proposed that these nontraditional hydrogen bonds could be a significant factor in stabilizing proteins, particularly membrane proteins as there is a low dielectric and no competition from water in the bilayer core. Nevertheless, this proposition has never been tested experimentally. Here, we report an experimental test of the significance of Cα−H···O bonds for protein stability. Thr24 in bacteriorhodopsin, which makes an interhelical Cα−H···O hydrogen bond to the Cα of Ala51, was changed to Ala, Val, and Ser, and the thermodynamic stability of the mutants was measured. None of the mutants had significantly reduced stability. In fact, T24A was more stable than the wild-type protein by 0.6 kcal/mol. Crystal structures were determined for each of the mutants, and, while some struct... |
| Databáze: | OpenAIRE |
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