Peptide design: Influence of a guest Aib-Pro segment on the stereochemistry of an Oligo-Val sequence—solution conformations and crystal structure of Boc-(Val)2-Aib-Pro-(Val)3-OMe
✍ Scribed by Isabella L. Karle; Judith L. Flippen-Anderson; K. Uma; Hemalatha Balaram; P. Balaram
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1990
- Tongue
- English
- Weight
- 719 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
SYNOPSIS
T h e peptide Boc-Val-Val-Aib-Pro-Val-Val-Val-OMe has been synthesized t o investigate the effect of introduction of a strong 8-turn promoting guest segment into a n oligopeptide with a tendency t o form extended structures. 'H-nmr studies in solution using analysis of N H group solvent accessibility and nuclear Overhauser effects suggest an appreciable solvent dependence of conformations. In chloroform a 310-helical structure is favored, while in dimethylsulfoxide a n Aib-Pro @-turn with extended arms on either side is suggested. In the crystal, the backbone forms a somewhat distorted 310-helix despite the presence of a Pro residue in the middle. Among the four possible intrahelical hydrogen bonds three are of the 4 + 1 type and one 5 -+ 1. Head-to-tail N H -. . O = C hydrogen bonds link the helical molecules into continuous columns. The space group is P2'2'2' with a = 11.320 ( 2) , b = 19.889(3), a n d c = 21.247(3) A. a Equivalent isotropic U defined as one-third of the trace of the orthogonalized U,, tensor.