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Ultraviolet Raman examination of the environmental dependence of bombolitin I and bombolitin III secondary structure

Holtz, JSW and Holtz, JH and Chi, Z and Asher, SA (1999) Ultraviolet Raman examination of the environmental dependence of bombolitin I and bombolitin III secondary structure. Biophysical Journal, 76 (6). 3227 - 3234. ISSN 0006-3495

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Abstract

Bombolitin I and III (BI and BIII) are small amphiphilic peptides isolated from bumblebee venom. Although they exist in predominately nonhelical conformations in dilute aqueous solutions, we demonstrate, using UV Raman spectroscopy, that they become predominately α-helical in solution at pH > 10, in high ionic Strength solutions, and in the presence of trifluoroethanol (TFE) and dodecylphosphocholine (DPC) micelles. In this paper, we examine the effects of electrostatic and hydrophobic interactions that control folding of BI and Bill by systematically monitoring their secondary structures as a function of solution conditions. We determine the BI and BIII secondary structure contents by using the quantitative UV Raman methodology of Chi et al. (1998. Biochemistry. 37:2854-2864). Our findings suggest that the α-helix turn in BIII at neutral pH is stabilized by a salt bridge between residues Asp2 and Lys5. This initial α-helical turn results in different BI and Bill α-helical folding mechanisms observed in high pH and high salt concentrations: BIII folds from its single α-helix turn close to its N-terminal, whereas the BI α-helix probably nucleates within the C- terminal half. We also used quasielastic light scattering to demonstrate that the BI and Bill α-helix formation in 0.2 M Ca(CIO4)2 is accompanied by formation of trimers and hexamers, respectively.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Holtz, JSW
Holtz, JH
Chi, Z
Asher, SAasher@pitt.eduASHER
Date: 1 January 1999
Date Type: Publication
Journal or Publication Title: Biophysical Journal
Volume: 76
Number: 6
Page Range: 3227 - 3234
DOI or Unique Handle: 10.1016/s0006-3495(99)77474-6
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Refereed: Yes
ISSN: 0006-3495
MeSH Headings: Bee Venoms--chemistry; Biophysical Phenomena; Biophysics; Hydrogen-Ion Concentration; Macromolecular Substances; Micelles; Osmolar Concentration; Peptides--chemistry; Phosphorylcholine--analogs & derivatives; Protein Conformation; Protein Structure, Secondary; Salts; Spectrum Analysis, Raman; Trifluoroethanol
Other ID: NLM PMC1300291
PubMed Central ID: PMC1300291
PubMed ID: 10354447
Date Deposited: 20 Mar 2013 16:42
Last Modified: 16 Feb 2019 15:55
URI: http://d-scholarship.pitt.edu/id/eprint/17806

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