FLUORESCENCE BEHAVIOUR OF SEQUENTIAL TYROSYL POLYPEPTIDES

Abstract— Fluorescence behaviour of three sequential tyrosyl copolypeptides, (Gly-Tyr)₃₅, (Ala-Tyr)₂₉ and (Val-Tyr)₂₂, was studied in alkaline solutions, in which ionisation of tyrosyl hydroxyl was 80%. Irradiation at 280 nm in all the three systems lead to the formation of a photoproduct which fluoresced intensely at 410 nm. The facility of the photoreaction depended markedly on the nature of the comonomer of tyrosine and the conformation of the polypeptide chain. As a result of photoproduct formation, the polypeptide backbone is hindered in acquiring more ordered structure at a lower degree of tyrosyl ionisation.