COLLAGEN-BASED STRUCTURES CONTAINING THE PEPTOID RESIDUE N-ISOBUTYLGLYCINE (NLEU) - SYNTHESIS AND BIOPHYSICAL STUDIES OF GLY-PRO-NLEU SEQUENCES BY CIRCULAR DICHROISM, ULTRAVIOLET ABSORBANCE, AND OPTICAL ROTATION

摘要

A peptoid residue N-isobutylglycine (Nleu) Mns introduced as a proline surrogate in collagen-like triple helical structures. A series of single chain and template-assembled collagen-based peptide-peptoid structures composed of Gly-Pro-Nleu sequences were prepared by solid-phase segment condensation methods. Both a synthetic route in solution and a solid phase method were employed to couple the KTA (cis,cis-1,3,5-trimethylcyclohexane-1,3 acid, also known as the Kemp triacid) based template, KTA-(Gly-OH)(3), to peptide-peptoid chains. Biophysical studies using CD, uv absorbance, and optical rotation measurements demonstrated that these compounds form triple-helical structures when the chains are longer than critical lengths. Results from melting curve measurements indicated that the Gly-Pro-Nleu sequence is comparable to the Gly-Pro-Pro sequence in stabilizing a triple-helical conformation. The KTA-based template stabilized triple-helical structures as can be seen by the increased melting temperatures as compared to equivalent single chain molecules. In addition, the template reduced the minimum chain length necessary to form a triple helix from sir to only three trimer repeats. (C) 1996 John Wiley & Sons, Inc. [References: 45]