Detail of "17186-60-6"

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The role of enhanced aromatic-electron donating aptitude of the tyrosyl side-chain with respect to that of phenylalanyl in intramolecular interactions

The role of enhanced aromatic-electron donating aptitude of the tyrosyl side-chain with respect to that of phenylalanyl in intramolecular interactions. Chass, G. A.; Lovas, S.; Murphy, R. F.; Csizmadia, I. G. (Department of Biomedical Sciences, School of Medicine Creighton University, Omaha, NE 68178, USA). 17186-60-6 and 6367-14-2 are cas registry numbers. These chemicals are also mentioned in this article. European Physical Journal D: Atomic, Molecular and Optical Physics, 20(3), 481-497 (English) 2002 Springer-Verlag. CODEN: EPJDF6. ISSN: 1434-6060. DOCUMENT TYPE: Journal CA Section: 34 (Amino Acids, Peptides, and Proteins) An exhaustive ab initio and DFT search for energetically stable conformers from the topol. possible set was undertaken on the N-acetyl-phenylalanyl-N-methylamide and N-acetyl-tyrosyl-N-methylamide systems. The geometries of all 81 phenylalanyl and 162 tyrosyl possible rotamers, described under the rules outlined by Multi-Dimensional Conformational Anal. (MDCA), were attempted at each of the RHF/3-21G, RHF/6-31G(d) and B3LYP/6-31G(d) levels of theory. A total of 32 and 66 stable conformational min. were found for the phenylalanyl and tyrosyl amino acid diamides, resp., at the B3LYP/6-31G(d) level. From the tyrosyl set, 33 unique conformers emerge when the orientation of the A3i dihedral angle (p-OH orientation) is disregarded. A total of 31 conformers were common to both sets and showed nearly identical geometries. The comparison of the optimized DFT geometries of the two systems showed near by perfect linear fits with R2 values of 0.9997, 0.9994, 0.9997, and 0.9996 for the fi, yi, A1i, and A2i dihedral angles, resp. Relative energies of the matching 31 conformers also fitted to a linear plot with an R2 value of 0.9985. The geometric centroid of the arom. ring in the side-chain of both systems was found to be within 4.1 ? of the H and O atoms of the peptide groups, in 21 and 2 of the conformers, resp. None of the non-matching conformers showed any such interaction distance ￡4.1 ?. .

N-Acetyl-L-phenylalanine-N-methylamide

N-Acetyl-L-phenylalanine-N-methylamide. Harada, Yoshinori; Iitaka, Yoichi (Fac. Pharm. Sci., Univ. Tokyo, Tokyo, Japan). Acta Crystallogr., Sect. B, B33(1), 247-9 (English) 1977. CODEN: ACBCAR. 17186-60-6 is the cas registry number. This chemical is also mentioned in this article. DOCUMENT TYPE: Journal CA Section: 75 (Crystallization and Crystal Structure) Section cross-reference(s): 34 The title compd., L-PhCH2CH(NHCOMe)CONHMe is monoclinic, space group P21, with a 11.695(1), b 4.966(1), c 11.531(1) .ANG., and .beta. 116.6(1).degree.; d.(calcd.) = 1.215 for Z = 2. The conformation of the mol. and the crystal packing closely resemble those of the DL-isomer. The torsion angles .phi.CN and .psi.CC are 106.7 and 103.8.degree., resp., which are very close to those given for the pleated-sheet polypeptide structure. .