Cystine Peptides. The Antiparallel \beta -Sheet Conformation of Two Synthetic Cyclic Bis( cystine peptides)

Kishore, R and Kumar, A and Balaram, P (1985) Cystine Peptides. The Antiparallel \beta -Sheet Conformation of Two Synthetic Cyclic Bis( cystine peptides). In: Journal of the American Chemical Society, 107 (26). pp. 8019-23.

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Abstract

Conformational studies on two synthetic cyclic bis(cystine peptides) have been carried out. The NMR data support a $C_2$-symmetric structure possessing four intramolecular hydrogen bonds in $CDCI_3$ and $(CD_3)_2$SO solutions. The involvement of the X-NH and NHMe groups in formation of transannular hydrogen bonds is inferred from the temperature and solvent dependences of NH chemical shifts, hydrogen-deuterium-exchange rates, and radical-induced line-broadening experiments. IR studies over a wide concentration range also favor hydrogen-bonded structures. Unusually low $C^\alpha H$ chemical shifts for $Cys^1$ and $Cys^3$ residues, high $^JHNC^\alpha H$ values (9H z), and the observation of nuclear Overhauser effects between $C_i^\alpha H$ and $N_i_+_1H$ protons in 1 provide compelling evidence for an antiparallel \beta -sheet conformation for the 22-membered cyclic bis(cystine peptides).

Item Type: Journal Article Journal of the American Chemical Society American Chemical Society Copyright belongs to American Chemical Society Division of Biological Sciences > Molecular Biophysics UnitDivision of Physical & Mathematical Sciences > Physics 28 Mar 2008 19 Sep 2010 04:43 http://eprints.iisc.ac.in/id/eprint/13525