Difference in the structures of alanine tri- and tetra-peptides with antiparallel ?-sheet assessed by X-ray diffraction, solid-state NMR and chemical shift calculations by GIPAW.
 

Difference in the structures of alanine tri- and tetra-peptides with antiparallel ?-sheet assessed by X-ray diffraction, solid-state NMR and chemical shift calculations by GIPAW.

http://www.bionmr.com//www.ncbi.nlm....x30_orange.png Related Articles Difference in the structures of alanine tri- and tetra-peptides with antiparallel ?-sheet assessed by X-ray diffraction, solid-state NMR and chemical shift calculations by GIPAW.

Biopolymers. 2014 Jan;101(1):13-20

Authors: Asakura T, Yazawa K, Horiguchi K, Suzuki F, Nishiyama Y, Nishimura K, Kaji H

Abstract
Alanine oligomers provide a key structure for silk fibers from spider and wild silkworms.We report on structural analysis of L-alanyl-L-alanyl-L-alanyl-L-alanine (Ala)4 with anti-parallel (AP) ?-structures using X-ray and solid-state NMR. All of the Ala residues in the (Ala)4 are in equivalent positions, whereas for alanine trimer (Ala)3 there are two alternative locations in a unit cell as reported previously (Fawcett and Camerman, Acta Cryst., 1975, 31, 658-665). (Ala)4 with AP ?-structure is more stable than AP-(Ala)3 due to formation of the stronger hydrogen bonds. The intermolecular structure of (Ala)4 is also different from polyalanine fiber structure, indicating that the interchain arrangement of AP ?-structure changes with increasing alanine sequencelength. Furthermore the precise (1)H positions, which are usually inaccesible by X-ray diffraction method, are determined by high resolution (1)H solid state NMR combined with the chemical shift calculations by the gauge-including projector augmented wave method.


PMID: 23526402 [PubMed - indexed for MEDLINE]



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