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Co‐oligopeptides of aromatic amino acids and glycine with a variable distance between the aromatic residues. III. Co‐oligopeptides of L ‐phenylalanine, L ‐tryptophan, and glycine: Synthesis and ultraviolet absorption properties
Author(s) -
Guarnaccia Rocco,
Rizzo Vincenzo,
Gianola Pietro,
Luisi Pier Luisi
Publication year - 1976
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1976.360150607
Subject(s) - chemistry , aromatic amino acids , molar absorptivity , oligopeptide , tryptophan , peptide , phenylalanine , glycine , chromophore , amino acid , side chain , absorption (acoustics) , peptide bond , stereochemistry , photochemistry , organic chemistry , biochemistry , physics , acoustics , optics , polymer
The preparation of the co‐oligopeptides of the series H‐Gly‐Phe‐(Gly) n ‐Trp‐Gly‐OH ( n = 0, 1, 2) and of other free peptides of glycine, L ‐tryptophan, and L ‐phenylalanine is reported. The syntheses have been carried out by conventional methods, using N ‐hydroxysuccinimide esters for the coupling steps. The ultraviolet absorption properties of the free peptides have been investigated in water. No hypo‐ or hyperchromicity was found for the aromatic chromophores, with the exception of H‐Gly‐Phe‐Trp‐OH, which shows a small but significant hypochromicity. The contribution of the peptide bond to the molar absorptivity in the far ultraviolet has been separated from that of the side chain plus the COO − group by plotting the measured molar absorptivity ϵ of the farthest accessible uv maximum as a function of the number of peptide bonds ( n A ). The peptide bond contribution proved to be independent of n A in the range n A = 1–5, thus ruling out the onset of helical conformations in the longer chain peptides.