Conformational studies of the C-terminal 16-amino-acid-residue fragment of the B3 domain of the immunoglobulin binding protein G from Streptococcus.

Biopolymers

Laboratory of Biopolymer Structure, Intercollegiate Faculty of Biotechnology, University of Gdańsk, Medical University of Gdańsk, Kładki 24, 80-822 Gdańsk, Poland.

Published: January 2009

AI Article Synopsis

  • The 16-amino-acid fragment IG(46-61) from the B3 domain of protein G was studied using CD and NMR spectroscopy and differential scanning calorimetry to assess its structure and stability.
  • The peptide maintains an organized three-dimensional structure resembling a beta-hairpin at various temperatures, stabilized by hydrophobic interactions among nonpolar side chains.
  • The melting temperature of the peptide is approximately 320 K, indicating its potential as a folding initiation site for the B3 domain of the immunoglobulin binding protein G.

Article Abstract

The structure and stability of the 16-amino-acid-residue fragment [IG(46-61)] corresponding to the C-terminal beta-hairpin of the B3 domain of the immunoglobulin binding protein G from Streptococcus was investigated by means of CD and NMR spectroscopy and by differential scanning calorimetry. The CD and 2D NMR experiments were carried out (i) in water at different temperatures and (ii) at one temperature (305 K), with only CD, at different TFE concentrations. Our results show that the IG(46-61) peptide possesses organized three-dimensional structure at all investigated temperatures. The three-dimensional structure of the IG(46-61) peptide resembles the general shape of a beta-hairpin that is also observed for this peptide in the experimental structure of the B3 domain in the whole G protein; the structure is stabilized by hydrophobic interactions between nonpolar side chains. Our study shows that the melting temperature of the IG(46-61) peptide is about 320 K which supports the hypothesis that the investigated peptide can serve as a folding initiation site of the B3 domain of the immunoglobulin binding protein G.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2766666PMC
http://dx.doi.org/10.1002/bip.21080DOI Listing

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