The α-Helix of Ribonuclease T 1as an Independent Stability Unit: Direct Comparison of Peptide and Protein Stability

Jeffrey K. Myers; Jeni S. Smith; C.Nick Pace; J.Martin Scholtz

doi:10.1006/jmbi.1996.0583

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The α-Helix of Ribonuclease T 1as an Independent Stability Unit: Direct Comparison of Peptide and Protein Stability

Journal article

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The α-Helix of Ribonuclease T 1as an Independent Stability Unit: Direct Comparison of Peptide and Protein Stability

Jeffrey K. Myers, Jeni S. Smith, C.Nick Pace and J.Martin Scholtz

Journal of molecular biology, Vol.263(3), pp.390-395

1996

DOI: 10.1006/jmbi.1996.0583

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Abstract

Measurements of the change in conformational stability, Δ(Δ G), upon mutation of two acidic residues at the C terminus of the helix of ribonuclease T 1have recently been reported. Here, we investigate peptides based on the sequence of the helix with the same mutations: Glu28 replaced with Gln, Asp29 replaced with Asn, and the double mutant. In addition, the mutant Lys25 to Gln was studied. Changes in helix content of the peptides with pH confirm the conclusion found in the intact protein, that the charged forms of the acidic residues destabilize the protein by destabilizing the helix. The pH-dependence of the change in confor mational free energy for the peptides and mutant proteins show fair correspondence for D29N and the double mutant. The mutants E28Q and K25Q, on the other hand, give striking agreement between the protein and peptide systems. This agreement suggests that the helix of ribonuclease T 1behaves as an independently stabilized structural unit of the intact protein and that stabilization of the helical form of the peptide is mirrored in the protein.

electrostatic interactions

independent stability unit

peptide

protein stability

α-helix

Details

Title: Subtitle: The α-Helix of Ribonuclease T 1as an Independent Stability Unit: Direct Comparison of Peptide and Protein Stability
Creators: Jeffrey K. Myers - Texas A&M University
Jeni S. Smith - Texas A&M University
C.Nick Pace - Texas A&M University
J.Martin Scholtz - Texas A&M University
Resource Type: Journal article
Publication Details: Journal of molecular biology, Vol.263(3), pp.390-395
Publisher: Elsevier Ltd
DOI: 10.1006/jmbi.1996.0583
ISSN: 0022-2836
eISSN: 1089-8638
Language: English
Date published: 1996
Academic Unit: Research Administration; Pharmaceutical Sciences and Experimental Therapeutics; Biochemistry and Molecular Biology; Chemistry
Record Identifier: 9984288730802771

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