Synthesis of Modified Amino Acids and Insertion in Peptides and Mimetics. Structural Aspects and Impact on Biological Activity.

De Marco, Rossella (2012) Synthesis of Modified Amino Acids and Insertion in Peptides and Mimetics. Structural Aspects and Impact on Biological Activity., [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Scienze chimiche, 24 Ciclo. DOI 10.6092/unibo/amsdottorato/4801.
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I studied the effects exerted by the modifications on structures and biological activities of the compounds so obtained. I prepared peptide analogues containing unusual amino acids such as halogenated, alkylated (S)- or (R)-tryptophans, useful for the synthesis of mimetics of the endogenous opioid peptide endomorphin-1, or 2-oxo-1,3-oxazolidine-4-carboxylic acids, utilized as pseudo-prolines having a clear all-trans configuration of the preceding peptide bond. The latter gave access to a series of constrained peptidomimetics with potential interest in medicinal chemistry and in the field of the foldamers. In particular, I have dedicated much efforts to the preparation of cyclopentapeptides containing D-configured, alfa-, or beta-aminoacids, and also of cyclotetrapeptides including the retro-inverso modification. The conformational analyses confirmed that these cyclic compounds can be utilized as rigid scaffolds mimicking gamma- or beta-turns, allowing to generate new molecular and 3D diversity. Much work has been dedicated to the structural analysis in solution and in the receptor-bound state, fundamental for giving a rationale to the experimentally determined bioactivity, as well as for predicting the activity of virtual compounds (in silico pre-screen). The conformational analyses in solution has been done mostly by NMR (2D gCosy, Roesy, VT, molecular dynamics, etc.). A special section is dedicated to the prediction of plausible poses of the ligands when bound to the receptors by Molecular Docking. This computational method proved to be a powerful tool for the investigation of ligand-receptor interactions, and for the design of selective agonists and antagonists. Another practical use of cyclic peptidomimetics was the synthesis and biological evaluation of cyclic analogues of endomorphin-1 lacking in a protonable amino group. The studies revealed that a inverse type II beta-turn on D-Trp-Phe constituted the bioactive conformation.

Tipologia del documento
Tesi di dottorato
De Marco, Rossella
Dottorato di ricerca
Scuola di dottorato
Scienze chimiche
Settore disciplinare
Settore concorsuale
Parole chiave
aminoacids mimetics mor, kor, dor integrine
Data di discussione
12 Aprile 2012

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