SYNTHESES AND PROPERTIES OF TERTIARY PEPTIDE-BOND CONTAINING-POLYPEPTIDES .2. TERTIARY PEPTIDE-BOND CONTAINING OLIGO(LEU)S - CONFORMATIONAL STUDIES IN SOLUTION OF OLIGO (L-LEUCINE)S WITH L-PROLINE RESIDUE AND GLYCYL-N-(2,4-DIMETHOXYBENZYL)-L-LEUCINE SEQUENCE

  • 1 January 1984
    • journal article
    • research article
    • Vol. 24  (1) , 14-24
Abstract
In order to elucidate the role of tertiary peptide bonds in the conformational development and solubility improvement of peptides, the conformational properties of oligo(Leu)s with the Pro residue and the Gly-(Dmob [2,4-dimethyoxybenzyl] Leu sequence were investigated in solution using IR absorption, CD [circular dichroism] and molar rotation measurements. The IR absorption spectroscopy indicated that the peptides soluble in inert solvents such as CCl4 and toluene had a predominantly .beta.-sheet structure in these solvents. The conformations of the peptides in CCl4 and toluene were essentially the same as those in a solid state, whereas in THF [tetrahydrofuran] and in MeOH, the peptides examined were efficiently subjected to solvation, and a randomly coiled structure was predominant. In order to confirm the randomly coiled structure, measurements were made of the molar rotations of the peptides in a variety of strong proton acceptor and donor solvents. CD measurements are also carried out in MeOH. The investigations showed that the protection of peptide bonds and the insertion of the Pro residue had the same effect on conformational and solubilizing behaviors and induced onset of an unordered structure and easy solvation oof the peptides in medium and high polarity-solvents.

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