Changes in global stability and local structure of cytochrome c upon substituting phenylalanine-82 with tyrosine

We have examined the F82Y;C102T variant of Saccharomyces cerevisiae iso-1-cytochrome c using high-resolution proton nuclear magnetic resonance spectroscopy, chemical denaturation, and differential scanning calorimetry. Comparison of proton chemical shifts, paramagnetic shifts, and nuclear Overhauser...

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Bibliographic Details
Published in:	Journal of inorganic biochemistry Vol. 51; no. 3; p. 663
Main Authors:	Greene, R M, Betz, S F, Hilgen-Willis, S, Auld, D S, Fencl, J B, Pielak, G J
Format:	Journal Article
Language:	English
Published:	United States 15-08-1993
Subjects:	Cytochrome c Group - chemistry Enzyme Stability Molecular Structure Phenylalanine - chemistry Saccharomyces cerevisiae - enzymology Tyrosine - chemistry
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Summary:	We have examined the F82Y;C102T variant of Saccharomyces cerevisiae iso-1-cytochrome c using high-resolution proton nuclear magnetic resonance spectroscopy, chemical denaturation, and differential scanning calorimetry. Comparison of proton chemical shifts, paramagnetic shifts, and nuclear Overhauser effects indicates structural changes are localized to the vicinity of position 82. One alteration involves the rearrangement of the side chain of leucine-85. Using many more proton assignments than were available in the initial report [G. J. Pielak, R. A. Atkinson, J. Boyd, and R. J. P. Williams, Eur. J. Biochem. 177, 179-185 (1988)], a second alteration involving an interaction between arginine-13 and tyrosine-82 is observed. The interaction appears to involve a hydrogen bond with the eta-protons of arginine's guanido group acting as donor and tyrosine's phenolic eta-oxygen as acceptor. In spite of this potentially-stabilizing interaction, the free energy of denaturation decreases by approximately 2.4 kcal mol-1. Results are discussed with respect to alterations in the native and denatured states.
ISSN:	0162-0134
DOI:	10.1016/0162-0134(93)85038-A