Conformational investigation of alpha,beta-dehydropeptides. XIII. Conformational properties of N-acetyl-alpha,beta-dehydrovaline N',N'-dimethylamide

• Published in: Acta biochimica polonica Vol. 51; no. 1; pp. 145 - 152
• Main Authors: Siodłak, Dawid, Rzeszotarska, Barbara, Broda, Małgorzata A, Kozioł, Anna E, Kołodziejczyk, Edyta
• Format: Journal Article
• Language: English
• Published: 31-03-2004
• ISSN: 0001-527X; 1734-154X
• DOI: 10.18388/abp.2004_3606

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.