Studies on lactams. VI. Stereochemistry of L-prolyl-L-valine anhydride.

Vibrational spectroscopic studies of L,D-alternating valine peptides

Raman and infrared spectra of Boc-(L-Val-D-Val),-OMe [(LD-Val),], with n = 4, 6 and 8, were obtained in crystalline and solution states. Based on predictions from normal-mode calculations of a number of relevant singleand double-stranded p-helix conformations, structures were assigned for the three oligopeptides under the abovementioned conditions. In the crystalline state, all three oligopepti...

A non-planar peptide bond in L-seryl-L-valine.

The molecular structure of (I) is shown in Fig. 1. Bond lengths and angles are normal, but the unusual non-planarity of the peptide bond is quite evident. The associated torsion angle C1ÐC3ÐN2ÐC4 (!) is 157.37 (15) , a deviation from 180 that is superceded among small chiral peptides only by the 156.6 ! angle in N-(tert-butoxycarbonyl)-l-Pro-l-Leu benzyl ester (Sugino et al., 1978). Fig. 2(a) s...

Cyclo­(-l-prolyl-l-valinyl-) from Burkholderia thailandensis MSMB43

THE TITLE COMPOUND [SYSTEMATIC NAME: (3S,8aS)-3-isopropyl-hexa-hydro-pyrrolo-[1,2-a]pyrazine-1,4-dione], C(10)H(16)N(2)O(2),, is a newly isolated cyclic dipeptide from Burkholderia thailandensis MSMB43. There are two independent mol-ecules in the asymmetric unit. Two C atoms and their attached H atoms in the five-membered ring of one of the mol-ecules are disordered over two sets of sites in a ...

Effect of urea on the optical rotatory dispersion of diketopiperazines of L-serine, L-alanine, L-lysine, L-valine, and L-valylglycine.

Crystal structure of γ-ethyl-l-glutamate N-carb­oxy anhydride

In the title compound (alternative name N-carboxy-l-glutamic anhydride γ-ethyl ester), C8H11NO5, the oxazolidine ring is essentially planar, with a maximum deviation of 0.019 (2) Å. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds between the imino group and the carbonyl O atom in the ethyl ester group, forming a tape structure along the c-axis direction. The oxazolidine rings of a...