โ Scribed by Andrea Motta; Delia Picone; Piero A. Temussi; Mauro Marastoni; Roberto Tomatis
No coin nor oath required. For personal study only.
The synthetic peptide of sequence H-Ala-Ser-Thr-Thr-Thr-Am-Tyr-Thr-OH, termed peptide T, a competitor of the Human Immunodeficiency Virus in the binding to human T cells, and its C -t d a l pentapeptide fragment, were studied by 'H-nmr in DMSO solution to determine conformational preferences. The observation of nuclear Overhauser enhancements (NO&) for both peptides, and unusual finding for small linear peptides, allowed complete sequence-specific r-ance assignments. Long-range NO& ring-current s h i h and the very small temperature coefficient of the Thr* NH chemical shifi suggest, for the zwitterionic form of peptide T, the preaence in solution of a involving T h r ' , Am6, Tyr' and Thr'. This conformational feature is consistent with previous structure-activity relationship studies indicating the invariance of the same reaidues in several potent pentapeptide analogues. The studied pentapeptide fragment, although lees structured, shows some tendency to fold even in a polar solvent such as DMSO.
Preliminary chemotaxis data on some pentapeptide analogues are consistent with our structural model.
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Thioredoxin can be cleaved enzymatically into the two fragments (1-73) and (74-108) and chemically into two different ones (1-37) and . In this paper, the conformational properties of the short fragment (1-37) are reported and compared with those of the larger fragment (1-73). Using mainly circular
## Synopsis A vibrational force field for the polypeptide chain has been developed for normal-mode analysis of such molecules. It can reproduce observed frequencies of known structures to within about 5 cm-l. We review the application of this technique to conformational problems in peptides (@-tur
The conformational preferences of peptide T (ASTTTNYT) were analysed by means of computational methods. A thorough exploration of the conformational space was carried out within the framework of the molecular mechanics approach, using simulated annealing as a searching strategy. Specifically, in ord