Stability enhancement of cytochrome c through heme deprotonation and mutations

Sonoyama Takafumi

Hasegawa Jun

Uchiyama Susumu

Nakamura Shota

Kobayashi Yuji

Sambongi Yoshihiro

Biophysical Chemistry

The chemical denaturation of Pseudomonas aeruginosa cytochrome c551 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.

Circular dichroism spectroscopy

Cytochrome c

Hydrogen bond

Protein stability

Heme propionate

Biology [ 460 ]

eng

Elsevier Science BV

Copyright (c) 2008 Elsevier B.V.

[ISSN] 0301-4622

[DOI] 10.1016/j.bpc.2008.09.020

[NCID] AA00566084

[DOI] http://dx.doi.org/10.1016/j.bpc.2008.09.020