N-t-Butyloxycarbonyl-S-benzylcysteinylglycine methyl ester

Abstract

Abstract.(CH3)3COCONHCH(CHzSCHzC6Hs)CONHCOOCH3 monoclinic, space group P2x, a=16.970(2), b= 5.022 (1), c= 12.142 (1) A~, and fl=96.99 (1) °. Qob~= 1"21, Q~a~= 1"24 gcm -3, Z=2. The structure was refined to R=0.064 for 1517 observed reflexions. The dihedral angle between the two peptide planes is 116.1 ° and the internal rotation angles ~, 9' and co in the peptide backbone are -124.0, 103.2 and 179.7 °, respectively. The molecules are joined together through N-H-..O hydrogen bonds (2.915 (8) and 3.024 (7) ~) in the b direction to form a parallel-chain pleated sheet.Introduction. The material was kindly supplied by Tanabe Seiyaku Co. Ltd., Osaka. The crystals obtained by slow evaporation from ethanol and water solution were needles elongated along the b axis. The systematic absence was 0k0, k odd. Lattice constants and intensities were measured from a crystal of dimensions 0"06 × 0"30 × 0"07 mm, on an automatic fourcircle diffractometer with Ni-filtered Cu Kc~ radiation using a scintillation counter with pulse-height analyser. The co/20-scan method was employed (scan speed: 4 ° min-1; scan range in 20:1.0+0.15 tan 0B, where 0B is Bragg angle). Background was measured for 10 s on either side of the peak. In total 1732 independent reflexions were surveyed up to 20 = 120 °, and 1517 nonzero reflexions were obtained. Corrections for Lorentz and polarization effects were applied, but no absorption correction was made [/t(Cu Kc0= 16-1 cm-1].The parameters of the sulphur atom were found in the Patterson map sharpened with B=4.4A 2. The minimum-function map calculated on the basis of these parameters revealed 23 non-hydrogen atoms (program

Proton magnetic resonance and conformational energy calculations of repeat pepetides of tropoelastin: the tetrapeptide

“…Initially a trans conformation with ]1 = 180°was assumed for the valyl side chain.86 We have assumed a O exo conformation for L-proline with X21, i.e., the N-C'l-Cd-C" torsion angle, equal to about -17°as found in p-Br-Cbz-Gly-L-Pro-L-Leu-Gly(OH).57 Hydrogen atoms were fixed at standard tetrahedral bond angles of 109.47°and bond lengths of 1.09 A to the L-prolyl side chain. The z-Boc group was assumed to be staggered about the C-O-C plane and was constructed with the dimensions reported by Kashino et al 58 for /V-zarz-butyloxycarbonyl-S-benzylcysteinylglycine methyl ester. The methoxy group was similarly assumed to be staggered about the C-O-C plane and was constructed with a bond angle for C-O-C equal to 110°and a tetrahedral geometry for the methyl group.89 A bond length of 1.42 A was assumed for the C-0 bond.…”

(2S)-Methyl 1-[(2R)-3-(benzylsulfanyl)-2-(tert-butoxycarbonylamino)propanoyl]pyrrolidine-2-carboxylate

“…1), was synthesized as an intermediate for l-cysteine-l-proline methyl ester. All bond lengths and angles are within normal ranges (Kashino et al, 1974;Oku et al, 2003). The observed distance of 3.853 (4) Å between the two C atoms (C9 and C14) is typical of the trans configuration, whereas the !…”

“…(N2-C9-C10-N1), are À147.0 (2) and 173.2 (2) , respectively. Hydrogen bonds are commonly found in peptide compounds (Kashino et al, 1974;Oku et al, 2003) and the structure of the title compound is stabilized by C-HÁ Á ÁO, C-HÁ Á ÁS and NC-HÁ Á ÁO hydrogen bonds (Table 1). The secondary structure of the title compound can be best described as a -pleated sheet-type arrangement.…”

Polymer Diffusion in a Dilute Solution. 2. Poly[bis(m-chlorophenoxy)phosphazene] in Chloroform

“…For ;1 (= ; -/2) and ,2 (= ; + /2), we get M;1 and M¡2 by means of eq 16 if b is known. It should be noted that the corresponding histogram steps in M space are no longer of equal magnitude with AMj = abs(M/2 -Mjx) (22) , = (Mj2 + Mji)/2 (23) In M space, we can transform G(r) dr such that G(r) dr becomes 2 ( )/*( ) "(6+1) dM where f{M) = f*(M)/ Y,f*{M)AMj. The particle scattering factor P(M) can be approximated by taking P(X) = 2(e~^~1 + X2)/X4, where X = Krg.…”