Hydrophobicity-induced pK shifts in elastin protein-based polymers

✍ Scribed by Dan W. Urry; Shao Qing Peng; Timothy M. Parker

• Publisher: Wiley (John Wiley & Sons)
• Year: 1992
• Tongue: English
• Weight: 522 KB
• Volume: 32
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360320413

✦ Synopsis

Abstract

Three polypentapeptides—poly[0.8(GVGVP), 0.2(GEGVP)], poly[0.8(GVGIP), 0.2‐(GEGIP)], and poly[0.75(GFGVP), 0.25(GEGVP)]—all analogues of the polypenta‐peptide of elastin—(Val^1^‐Pro^2^‐Gly^3^‐Val^4^‐Gly^5^)~n~ or poly(VPGVG)—have been prepared to determine the effect of changing the hydrophobicity, i.e., Val^1^ → Ile^1^ (I) and Val^4^ → Phe^4^ (F), on the pK~a~ and the temperature dependence of pK~a~ of the Glu (E) residue. Shifts in pK~a~ as large as 1.7 units are observed and the temperature dependence is much steeper for the structure‐dependent proximity of the more hydrophobic Ile^1^ residues to the Glu^4^ residue. Even though this system is dominated by the inverse temperature transition of hydrophobically driven folding on raising the temperature, the effect of adding 0.15 N NaCl is to suppress the hydrophobicity‐induced pK~a~ shift.