Stability enhancement of cytochrome c through heme deprotonation and mutations |
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Authors: | Sonoyama Takafumi Hasegawa Jun Uchiyama Susumu Nakamura Shota Kobayashi Yuji Sambongi Yoshihiro |
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Institution: | Graduate School of Biosphere Science, Hiroshima University, CREST of Japan Science and Technology Corporation, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8528, Japan. |
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Abstract: | The chemical denaturation of Pseudomonas aeruginosa cytochrome c(551) variants was examined at pH 5.0 and 3.6. All variants were stabilized at both pHs compared with the wild-type. Remarkably, the variants carrying the F34Y and/or E43Y mutations were more stabilized than those having the F7A/V13M or V78I ones at pH 5.0 compared with at pH 3.6 by ~3.0-4.6 kJ/mol. Structural analyses predicted that the side chains of introduced Tyr-34 and Tyr-43 become hydrogen donors for the hydrogen bond formation with heme 17-propionate at pH 5.0, but less efficiently at pH 3.6, because the propionate is deprotonated at the higher pH. Our results provide an insight into a stabilization strategy for heme proteins involving variation of the heme electronic state and introduction of appropriate mutations. |
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Keywords: | GdnHCl guanidine hydrochloride PA c551 cytochrome c551 from Pseudomonas aeruginosa CD circular dichroism |
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