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The role of a trans-proline in the folding mechanism of ribonuclease T1

Title data

Schindler, Thomas ; Mayr, Lorenz M. ; Landt, Olfert ; Hahn, Ulrich ; Schmid, Franz X.:
The role of a trans-proline in the folding mechanism of ribonuclease T1.
In: European Journal of Biochemistry. Vol. 241 (15 October 1996) Issue 2 . - pp. 516-524.
ISSN 0014-2956
DOI: https://doi.org/10.1111/j.1432-1033.1996.00516.x

Abstract in another language

Protein folding is often retarded by the cis reversible trans isomerizations of prolyl peptide bonds both in vitro and in vivo. An important role for the folding mechanism is well established for the prolyl peptide bonds that are cis in the native protein, but not for those that are trans. Here we investigated the role of trans-Pro73 for the folding of ribonuclease T1 (which additionally contains two cis-prolines) by comparing the wild-type protein with the Pro73-->Val variant. The Pro-->Val substitution led to a destabilization of the folded protein by 8.5 kJ/mol, which is explained by the strong, 25-fold increase in the rate of unfolding. In contrast, the rates and amplitudes of the fast and slow refolding reactions were virtually unchanged. trans-Proline residues remain largely trans after unfolding, and therefore their contributions to the observed folding kinetics should indeed be insignificant for proteins which also contain one or more cis prolines. The cis-proline residues dominate the kinetics of refolding, because almost all slow-folding molecules contain the respective incorrect (trans) isomers, and because trans-->cis isomerizations are slower than cis-->trans isomerizations. The inability to detect contributions from a trans-proline to the kinetics of folding does not imply that this proline is non-essential for folding in the sense that its cis reversible trans isomerization is energetically uncoupled from conformational folding.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: PubMed-ID: 8917450
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Former Professors > Professorship Biochemistry - Univ.-Prof. Dr. Franz Xaver Schmid
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Professorship Biochemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Former Professors
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 540 Chemistry
Date Deposited: 18 May 2015 08:21
Last Modified: 18 May 2015 08:21
URI: https://eref.uni-bayreuth.de/id/eprint/13518