Conformational investigation of alpha,beta-dehydropeptides. XIII. Conformational properties of N-acetyl-alpha,beta-dehydrovaline N',N'-dimethylamide.
The crystal structure of Ac-DeltaVal-NMe(2) (DeltaVal = alpha,beta-dehydrovaline) was determined by X-ray crystallography. The found angles phi = -60 degrees and psi = 125 degrees correspond exactly to the respective values of the (i + 1)th residue in idealised beta-turn II/VIa. Ab initio/DFT studies revealed that the molecule adopts the angle psi restricted only to about |130 degrees | and very readily attains the angle phi = about -50 degrees. This is in line with its solid-state conformation. Taken together, these data suggest that the DeltaVal residue combined with a C-terminal tertiary amide is a good candidate at the (i + 1)th position in a type II/VIa beta-turn.
Siodłak
Dawid
D
Institute of Chemistry, University of Opole, Opole, Poland.
Rzeszotarska
Barbara
B
Broda
Małgorzata A
MA
Kozioł
Anna E
AE
Kołodziejczyk
Edyta
E
D000577:Amides / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008968:Molecular Conformation; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D013816:Thermodynamics; D014633:Valine / Q000737:chemistry*
D000577:Amides; D010455:Peptides; D014633:Valine