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Influence of amino acid specificities on the molecular and supramolecular organization of glycine‐rich elastin‐like polypeptides in water
Author(s) -
Salvi Anna M.,
Moscarelli Pasquale,
Satriano Giuseppina,
Bochicchio Brigida,
Castle James E.
Publication year - 2011
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.21636
Subject(s) - chemistry , moiety , supramolecular chemistry , elastin , pentapeptide repeat , hydrogen bond , stereochemistry , crystallography , biophysics , molecule , biochemistry , peptide , organic chemistry , crystal structure , medicine , pathology , biology
Elastin‐like polypeptides adopt complex supramolecular structures, showing either a hydrophobic or a hydrophilic surface, depending on their surrounding environment and the supporting substrate. The preferred organization is important in many situations ranging from biocompatibility to bio‐function. Here we compare the n‐repeat pentamer LeuGlyGlyValGly ( n = 7) with the analogue ValGlyGlyValGly ( n = 5), as water suspensions and as deposits on silicon substrates. These sequences contain the repeat XxxGlyGlyZzzGly (Xxx, Zzz = Val, Leu) motif belonging to the hydrophobic glycine‐rich domain of elastin and represent a simplified model from which to obtain information on molecular interactions functional to elastin itself. The compounds studied differ only by the presence of the CH 2 spacer in the Leu moiety and thus the work was aimed at revealing the influence of this spacer element on self assembly. Both polypeptides were studied under identical conditions, using combined techniques, to identify differences in their conformational states both at molecular (CD, FTIR) and supramolecular (XPS, AFM) levels. By these means, together with a Congo Red spectroscopic assay of β‐sheet formation in water, a clear correlation between amino acid sequences (sequence specificity) and their kinetics and ordering of aggregation has emerged. The novel outcomes of this work are from the supplementary measurements, made to augment the AFM and XPS studies, showing that the significant step in the self assembly of both polypeptides takes place in the liquid phase and from the finding that the substitution of Val by Leu in the first position of the pentapeptide effectively inhibits the formation of amyloidal fibers. © 2011 Wiley Periodicals, Inc. Biopolymers 95: 702–721, 2011.