Conformational Analysis of Dolavaline, Dolaisoleuine, Dolaproine and Dolaphenine Unusual Amino Acids

Abstract

As the conformational analysis plays a significant role in molecular biology, different theoretical and experimental methods have been devoted to this subject in the last 30 years. The conformational properties of the most common amino acids have been extensively investigated employing different theoretical methods and experimental techniques. From a theoretical point of view, the empirical methods (i.e molecular mechanics, non-bonded) have demonstrated to give results close to those obtained from more sophisticated quantum mechanical ones with very low computational efforts. So, the theoretical investigation of structure, conformational flexibility, solvent effects and dynamical properties of amino acid residues, peptides, polipeptides, proteins and nucleic acid segments is now possible by using empirical potentials and parameters largely tested in literature. The knowledge of the conformational properties of amino acid residues becomes very useful for the study of more complex peptide and protein structures In this paper we report the conformational analysis of four unusual amino acid residues: (dolavaline, dolaisoleuine, dolaproine and dolaphenine performed employing the non bonded method. These unusual amino acids have been recently found in the dolastatin 10 pentapeptide extracted from sea hare Dolabella Auricularia [1–4]. Since dolastatin 10 is one of the most powerful (i.e., lowest in vivo dose) antineoplastic substance known to date [2], the study of its constituent can contribute to the investigation of its structure and to the possible explanation of its biological activity.KeywordsTorsional AngleConformational PropertyConformational AnalysisMinimum RegionCommon Amino AcidThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.