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Protein & Peptide Letters

Editor-in-Chief

ISSN (Print): 0929-8665
ISSN (Online): 1875-5305

Nanopore Analysis of the Effect of Metal Ions on the Folding of Peptides and Proteins

Author(s): Jeremy S. Lee

Volume 21, Issue 3, 2014

Page: [247 - 255] Pages: 9

DOI: 10.2174/09298665113209990075

Price: $65

Abstract

In this minireview, the nanopore analysis of peptides and proteins in the presence of divalent metal ions will be surveyed. In all cases the binding of the metal ions causes the peptide or protein to adopt a more compact conformation which can no longer enter the α-hemolysin pore. In the absence of Zn(II) the 30-amino acid Zn-finger peptide can readily translocate the pore; but upon addition of Zn(II) the peptide folds and only bumping events are observed. Similarly, the octapeptide repeat from the N-terminus of the prion protein binds Cu(II), which prevents it from translocating. The fulllength prion protein also undergoes conformational changes upon binding Cu(II), which results in an increase in the proportion of bumping events. Myelin basic protein of 170 residues is intrinsically disordered and, perhaps surprisingly, for a basic protein of this size, can translocate against the electric field based on the observation that the event time increases with increasing voltage. It, too, folds into a more compact conformation upon binding Cu(II) and Zn(II), which prevents translocation. Finally even proteins such as maltose binding protein which does not contain a formal binding site for metal ions undergoes conformational changes in the presence of the metal chelator, EDTA. Thus, contamination of proteins with trace metal ions should be considered when studying proteins and peptides by nanopore analysis.

Keywords: α-hemolysin, divalent metal ions, intrinsically disordered proteins, nanopore analysis, protein misfolding, translocation.


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