FLUORESCENCE, PHOTODESTRUCTION, PHOTOIONIZATION AND THERMAL-DEGRADATION OF O-PHTHALALDEHYDE BETA-MERCAPTOETHANOL-LABELED ALIPHATIC ALPHA-OLIGOPEPTIDES/

Photophysical and photochemical properties of o-phthalaldehyde/beta-me rcaptoethanol-labelled aliphatic alpha-peptides were investigated. It is found that alpha-peptide derivatives have lower fluorescence quantu m yields, higher photodestruction quantum yields and lower yields for formation of solvated electrons as compared to amino acid and simple a lkylamine derivatives in aqueous alkaline solution. These properties o f the alpha-peptide derivatives sets narrow limits for their utilizati on in laser-based (high light intensity) detector systems. In contrast , the thermal stability of the peptide derivatives was found to be sev eralfold higher than for the parent amino acid derivatives. The differ ential rates of thermal derivative degradation could be utilized in a new approach towards selective determination of peptides.