Development of New Synthetic Methodologies for Selenocysteine, Selenopeptides and β-Seleno Amino Acids”

Abstract

thesis mainly describes the synthesis and characterization of novel selenium-containing amino acids for their potential application in redox reactions. Several β-seleno-α-amino acids have been synthesized and fully characterized by 1H, 13C, 77Se NMR Spectroscopy and mass spectrometry. These amino acids have been synthesized with the view that these unnatural amino acids may be useful for synthesizing peptides with restricted conformational change, stabilizing defined secondary structure in proteins, increasing the lipophilicity of peptides and proteins, providing resistance to enzymatic hydrolysis and application as enzyme inhibitors. It is known that β-Hydroxy/sulpho-α-amino acids are present in numerous biologically active natural products such as glycopeptides vancomycin, bouvardin, orienticins, phomopsins and ristocetin. The unnatural amino acids synthesized in this study include, three isomers of the selenium analogues of threonine (S12-S14), the phenylalanine analogue (S15), tyrosine derivative (S16), the protected amino acid having p-nitrophenyl moiety (S17) and also the SeCN derivative of all these three aminoacids S18-20 (Figure S4). The tryptophan analogue having a selenenyl cyanide moiety (S21) could not isolate. The reduction of the diselenide bonds and -SeCN in compounds S3-S10/S18-S20 would provide the amino acids in the corresponding selenol forms.