ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The crystal structure of (Z)-acetyl-α,β-dehydrophenylalanine methylamide (monoclinic Cc, a = 10.241(1), b = 15.252(1), c = 8.643(1) Å, β = 120.98(1)°, Z = 4) has been solved by x-ray diffraction to an R-factor = 0.148, and compared to that of the homologous L-phenylalanine dervative. Molecules are intermolecularly hydrogen-bonded to four neighboring molecules in a three-dimensional network with alternating layers of interacting amide bonds and orthogonally arranged phenyl rings. The existence of the Cα = Cβ double bond results in a phenyl orientation that is forbidden for phenylananine (χ1 = -7,8°), and in shorter Cα - Cβ and Cβ - Cγ distances. The geometrical paramenters of the peptide backbone are not drastically modified by α,β-unsaturation. However, the N-Cα-C′ angle is increased by nearly 5°, and the dimensions, and therefore probably the electronic conjugation, of the N-terminal amide group to be affected by the occurrence of the vicinal Cα = Cβ double bond.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360240405
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