Biomaterial Database

Theoretical pi-pi absorption and circular dichroic spectra of beta-turn model peptides. 1986

B K Sathyanarayana, and J Applequist

The dipole interaction model, treated by the partially dispersive normal mode method, is used to calculate pi-pi absorption and circular dichroic spectra of beta-turn model peptides in certain conformations. These include Ac-Gly-Gly-NHMe, Ac-L-Ala-L-Ala-NHMe, and Ac-L-Ala-Gly-NHMe in the standard beta-turn conformations I, II, and III of Venkatachalam and cyclo(L-Ala-Gly-epsilon-aminocaproyl), cyclo(L-Ala-L-Ala-epsilon-aminocaproyl), and cyclo(L-Ala-D-Ala-epsilon-aminocaproyl) in the minimum-energy conformations of Nemethy et al. Boltzmann average circular dichroic spectra of the cyclic compounds agree with experimental spectra in most respects. The results are compared with previous theoretical CD spectra for these molecules and with conformational assignments based on other evidence. Absorption spectra in the pi-pi band are predicted to be moderately sensitive to conformation.

UI	MeSH Term	Description	Entries
D008956	Models, Chemical	Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.	Chemical Models,Chemical Model,Model, Chemical
D010455	Peptides	Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are considered to be larger versions of peptides that can form into complex structures such as ENZYMES and RECEPTORS.	Peptide,Polypeptide,Polypeptides
D010456	Peptides, Cyclic	Peptides whose amino acid residues are linked together forming a circular chain. Some of them are ANTI-INFECTIVE AGENTS; some are biosynthesized non-ribosomally (PEPTIDE BIOSYNTHESIS, NON-RIBOSOMAL).	Circular Peptide,Cyclic Peptide,Cyclic Peptides,Cyclopeptide,Orbitide,Circular Peptides,Cyclopeptides,Orbitides,Peptide, Circular,Peptide, Cyclic,Peptides, Circular
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D002942	Circular Dichroism	A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism