A large class of naturally occurring compounds like antibiotics, toxins, hormones, ion transport regulators and other biologically active compounds are cyclic peptides. Synthetic cyclic peptides of defined backbone conformation are potentially useful as analogs for determining biologically active conformations of naturally occurring peptides. The conformational restrictions imposed by cyclisation make cyclic peptides excellent model compounds for the study of the protein conformation. Many cyclic peptides also take part in the transport of ions across biological membranes. X-ray crystallography is a fine tool to determine the conformational features of cyclic peptides. The conformation of a molecule is intimately related to its biological activity and the study of the conformation of cyclic peptides crystallized under different conditions and comparison of the results with those obtained from other methods such as spectroscopic techniques would be very valuable. In this project using X-ray diffraction technique the examination of the structure and conformation of a few synthetic cyclic peptides which are useful as analogs for biologically active molecules and the study of metal ion complexes of cyclic peptides which are useful in understanding the ion transport mechanism across the biological membrane are planned.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Biophysics and Biophysical Chemistry A Study Section (BBCA)
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Roswell Park Cancer Institute Corp
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Thomas, L M; Ramasubbu, N; Bhandary, K K (1994) Structural characteristics of diproline: a new crystal form of tBoc-Pro-Pro-OH. Int J Pept Protein Res 44:207-14
Thomas, L M; Ramasubbu, N; Bhandary, K K (1994) Crystal structure of cyclo(Pro-Gly)3:Li complex: a model for ion transport by cyclo(Pro-Gly)3. Biopolymers 34:1007-13
Thomas, L M; Ramasubbu, N; Bhandary, K K et al. (1994) A new class of substituted 1,2,4-triazolo-1,3,4-thiadiazepines. Acta Crystallogr C 50 ( Pt 10):1608-12
Bhandary, K K; Chauhan, V S (1993) Peptide design 3(10)-helical conformation of a linear pentapeptide containing two dehydrophenylalanines, Boc-Gly-delta ZPhe-Leu-delta ZPhe-Ala-NHCH3. Biopolymers 33:209-17
Bharadwaj, A; Singh, M; Bhandary, K et al. (1993) Conformationally constrained formyl methionyl tripeptides: structure-function study of analogs containing alpha,beta-dehydrophenylalanine and dehydroleucine. Pept Res 6:298-307
Chauhan, V S; Bhandary, K K (1992) Crystal structure and conformation of a highly constrained linear tetrapeptide Boc-Leu-dehydro Phe-Ala-Leu-OCH3. Int J Pept Protein Res 39:223-8
Bhandary, K K; Kopple, K D (1991) Conformation of cyclic octapeptides. VI. Structure of cyclo-bis-(-L-alanyl-glycyl-L-prolyl-L-phenylalanyl-) tetrahydrate. Acta Crystallogr C 47 ( Pt 7):1483-7
Bhandary, K K (1991) Conformation of cyclo-bis(-L-valyl-L-proplyl-D-alanyl-), a synthetic cyclic hexapeptide. Acta Crystallogr C 47 ( Pt 6):1280-3
Raj, P A; Soni, S D; Ramasubbu, N et al. (1990) Crystal structure and solution conformation of S,S'-bis(Boc-Cys-Ala-OMe): intramolecular antiparallel beta-sheet conformation of an acyclic cystine peptide. Biopolymers 30:73-85
Bhandary, K K; Senadhi, S E; Prasad, K U et al. (1990) Conformation of a cyclic decapeptide analog of a repeat pentapeptide sequence of elastin: cyclo-bis(valyl-prolyl-alanyl-valyl-glycyl). Int J Pept Protein Res 36:122-7

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