Abstract
We have investigated the folding energy landscape of cytochrome c by exploiting the widely different electron-transfer (ET) reactivities of buried and exposed Zn(II)-substituted hemes. An electronically excited Zn-porphyrin in guanidine hydrochloride denatured Zn-substituted cytochrome c (Zn-cyt c) reduces ruthenium(III) hexaammine about ten times faster than when embedded in the fully folded protein. Measurements of ET kinetics during Zn-cyt c folding reveal a burst intermediate in which one-third of the ensemble has a protected Zn-porphyrin and slow ET kinetics; the remaining fraction exhibits fast ET characteristic of a solvent-exposed redox cofactor. The ET data show that, under solvent conditions favoring the folded protein, collapsed non-native structures are not substantially more stable than extended conformations, and that the two populations interchange rapidly. Most of the folding free energy, then, is released when compact structures evolve into the native fold.
| Original language | English |
|---|---|
| Pages (from-to) | 159-164 |
| Number of pages | 6 |
| Journal | Journal of Molecular Biology |
| Volume | 320 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 2002 Jan 1 |
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Keywords
- Burst intermediate
- Cytochrome c
- Electron transfer
- Protein folding
ASJC Scopus subject areas
- Molecular Biology
Cite this
The cytochrome c folding landscape revealed by electron-transfer kinetics. / Lee, Jennifer C.; Chang, I-Jy; Gray, Harry B.; Winkler, Jay R.
In: Journal of Molecular Biology, Vol. 320, No. 2, 01.01.2002, p. 159-164.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The cytochrome c folding landscape revealed by electron-transfer kinetics
AU - Lee, Jennifer C.
AU - Chang, I-Jy
AU - Gray, Harry B.
AU - Winkler, Jay R.
PY - 2002/1/1
Y1 - 2002/1/1
N2 - We have investigated the folding energy landscape of cytochrome c by exploiting the widely different electron-transfer (ET) reactivities of buried and exposed Zn(II)-substituted hemes. An electronically excited Zn-porphyrin in guanidine hydrochloride denatured Zn-substituted cytochrome c (Zn-cyt c) reduces ruthenium(III) hexaammine about ten times faster than when embedded in the fully folded protein. Measurements of ET kinetics during Zn-cyt c folding reveal a burst intermediate in which one-third of the ensemble has a protected Zn-porphyrin and slow ET kinetics; the remaining fraction exhibits fast ET characteristic of a solvent-exposed redox cofactor. The ET data show that, under solvent conditions favoring the folded protein, collapsed non-native structures are not substantially more stable than extended conformations, and that the two populations interchange rapidly. Most of the folding free energy, then, is released when compact structures evolve into the native fold.
AB - We have investigated the folding energy landscape of cytochrome c by exploiting the widely different electron-transfer (ET) reactivities of buried and exposed Zn(II)-substituted hemes. An electronically excited Zn-porphyrin in guanidine hydrochloride denatured Zn-substituted cytochrome c (Zn-cyt c) reduces ruthenium(III) hexaammine about ten times faster than when embedded in the fully folded protein. Measurements of ET kinetics during Zn-cyt c folding reveal a burst intermediate in which one-third of the ensemble has a protected Zn-porphyrin and slow ET kinetics; the remaining fraction exhibits fast ET characteristic of a solvent-exposed redox cofactor. The ET data show that, under solvent conditions favoring the folded protein, collapsed non-native structures are not substantially more stable than extended conformations, and that the two populations interchange rapidly. Most of the folding free energy, then, is released when compact structures evolve into the native fold.
KW - Burst intermediate
KW - Cytochrome c
KW - Electron transfer
KW - Protein folding
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UR - http://www.scopus.com/inward/citedby.url?scp=0036293508&partnerID=8YFLogxK
U2 - 10.1016/S0022-2836(02)00466-7
DO - 10.1016/S0022-2836(02)00466-7
M3 - Article
C2 - 12079375
AN - SCOPUS:0036293508
VL - 320
SP - 159
EP - 164
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
SN - 0022-2836
IS - 2
ER -