Karle, IL and Anderson, Flippen JL and Kishore, R and Balaram, P (1989) Cystine peptides Antiparallel β-sheet conformation of the cyclic biscystine peptide [Boc-Cys-Ala-Cys-NHCH3]2. In: International Journal of Peptide & Protein Research, 34 (1). pp. 37-41.
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The crystal structure analysis of the cyclic biscystine peptide [Boc-Cys1-Ala2-Cys3-NHCH3]2 with two disulfide bridges confirms the antiparallel ?-sheet conformation for the molecule as proposed for the conformation in solution. The molecule has exact twofold rotation symmetry. The 22-membered ring contains two transannular NH ? OC hydrogen bonds and two additional NH ? OC bonds are formed at both ends of the molecule between the terminal (CH3)3COCO and NHCH3 groups. The antiparallel peptide strands are distorted from a regularly pleated sheet, caused mainly by the L-Ala residue in which ?=ï¿½ 155° and ?= 162°. In the disulfide bridge C? (1)-C? (1)-S(1)-(3')-C?(3')-C?(3'), Sï¿½S = 2.030 Å, angles C? SS = 107° and 105°, and the torsional angles are ï¿½49, ï¿½104, +99, ï¿½81, ï¿½61Â°, respectively. The biscystine peptide crystallizes in space group C2 with a = 14.555(2) Ã…, b = 10.854(2) Ã…, c = 16.512(2)Ã…, and ?= 101.34(1) with one-half formula unit of C30H52N8O10S4Â· 2(CH3)2SO per asymmetric unit. Least-squares refinement of 1375 reflections observed with |F| > 3?(F) yielded an R factor of 7.2%.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to John Wiley & Sons.|
|Keywords:||crystal structure;disulfide bridges;torsional angles ;22-membered ring ;twisted ?-sheet|
|Department/Centre:||Division of Biological Sciences > Molecular Biophysics Unit|
|Date Deposited:||03 Jun 2010 09:51|
|Last Modified:||22 Sep 2010 05:06|
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