Sequence recombination improves target specificity in a redesigned collagen peptide abc-type heterotrimer.

Stability of the collagen triple helix is largely governed by its imino acid content, namely the occurrence of proline and 4R-hydroxyproline at the X and Y positions respectively of the periodic (Gly-X-Y)(n) sequence. Although other amino acids at these positions reduce stability of the triple helix, this can be partially compensated by introducing intermolecularsidechain salt bridges. This approach was previously used to design an abc-type heterotrimer composed of one basic,one acidic and one neutral imino acid rich chain (Gauba & Hartgerink, 2007). In this study, an abc-type heterotrimer was designed to be the most stable species using a sequence recombination strategy that preserved both the amino acid composition and the network of interchain salt-bridges of the original design. The target heterotrimer had the highest T(m) of 50°C, 7°C greater than the next most stable species. Stability of the heterotrimer decreased with increasing ionic strength, consistent with the role of intermolecular salt bridges in promoting stability. Quantitative meta-analysis of these results and published stability measurements on closely related peptides was used to discriminate the contributions of backbone propensity and sidechain electrostatics to collagen stability. Proteins 2012. © 2012 Wiley Periodicals, Inc. Copyright © 2012 Wiley Periodicals, Inc.