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Effect of salts on the structural behavior of hPrP α2‐helix‐derived analogues: the counterion perspective
Author(s) -
Ronga Luisa,
Palladino Pasquale,
Tizzano Barbara,
Marasco Daniela,
Benedetti Ettore,
Ragone Raffaele,
Rossi Filomena
Publication year - 2006
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/psc.818
Subject(s) - chaotropic agent , chemistry , counterion , helix (gastropod) , hofmeister series , peptide , fibril , conformational change , salt (chemistry) , ion , protein structure , molecular dynamics , biophysics , crystallography , stereochemistry , biochemistry , computational chemistry , organic chemistry , ecology , snail , biology
Both theoretical studies and direct experimental evidence have emphasized the importance of electrostatic interactions in the general phenomenon of spontaneous amyloid fibril formation. A number of observations have recently spurred interest in the contribution of these interactions to the conformational behavior of the prion protein. In this paper, we show how salt addition and pH change can modify the conformation of two peptide analogues derived from the human prion protein helix 2 according to a Hofmeister‐series‐type dependence. Employment of various sodium salts allowed us to highlight the fact that chaotropic anions favor unstructured conformation, whereas kosmotropic anions promote the formation of compact structures like α‐helix and β‐sheet, which may ultimately facilitate fibril formation. This finding should warn people engaged in ion‐based research on prion and derived peptides about cation‐bound effects, which have been almost exclusively investigated to date, being easily confounded with modifications that are actually caused by anion activity, thus leading researchers into misunderstand ion‐specific effects. To avoid the common complication of ion confounding, it is highly desirable that experiments be designed so that the species causing the modification can be unequivocally perceived. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.