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Destabilization of a protein helix by electrostatic interactions

Titelangaben

Walter, Stefan ; Hubner, Bernd ; Hahn, Ulrich ; Schmid, Franz X.:
Destabilization of a protein helix by electrostatic interactions.
In: Journal of Molecular Biology. Bd. 252 (1995) Heft 1 . - S. 133-143.
ISSN 0022-2836
DOI: https://doi.org/10.1006/jmbi.1995.0480

Abstract

Electrostatic interactions between charged residues and the helix dipole in a protein were investigated by protein engineering methods. In ribonuclease T1, two surface-exposed acidic residues (Glu28 and Asp29) are located near the carboxyl terminus of the alpha-helix between residues 13 and 29. They were replaced, individually and in concert, by the uncharged amides Gln28 and Asn29, and the stabilities of the wild-type protein and its variants were determined as a function of pH. The effects of the two mutations are additive. Either one leads to a marginal destabilization by 0.7 kJ/mol at pH 2 but to a strong stabilization by about 3.2 kJ/mol at pH 7. This suggests that the deprotonations of Glu28 and Asp29 reduce the free energy of stabilization of folded ribonuclease T1 by about 4 kJ/mol each. This destabilization is probably caused by unfavorable electrostatic interactions of Glu28 and Asp29 with the negative end of the helix dipole. The activation energies for the unfolding of the different variants of ribonuclease T1 change in parallel with the differences in the thermodynamic stability when the pH is varied. This indicates that the unfavorable electrostatic interactions of Glu28 and Asp29 are lost very early in unfolding, and are not present in the activated state of unfolding.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Zusätzliche Informationen: PubMed-ID: 7666425
Institutionen der Universität: Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie > Ehemalige Professoren > Professur Biochemie - Univ.-Prof. Dr. Franz Xaver Schmid
Fakultäten
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie > Professur Biochemie
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie > Ehemalige Professoren
Titel an der UBT entstanden: Nein
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik > 540 Chemie
Eingestellt am: 18 Mai 2015 06:06
Letzte Änderung: 08 Jul 2022 13:27
URI: https://eref.uni-bayreuth.de/id/eprint/13511