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PHOTOLYSIS MECHANISM OF AQUEOUS TYROSINE AND TYROSYL PEPTIDES *
Author(s) -
Baugher J. F.,
Grossweiner L. I.
Publication year - 1978
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1978.tb07692.x
Subject(s) - chemistry , photodissociation , flash photolysis , photochemistry , intramolecular force , aqueous solution , radical , tyrosine , stereochemistry , organic chemistry , kinetics , reaction rate constant , biochemistry , physics , quantum mechanics
— Laser flash photolysis at 265 nm has been employed for measuring the initial hydrated electron (e ‐ aq ) and p ‐alanylphenoxyl radical (Tyr) in aqueous Tyr, small Tyr peptides and R Nase A. The results indicate that monophotonic photolysis not involving the fluorescent or triplet states is the principal initial process. Equivalent yields of e and Tyr were found in all cases except Tyr, where the Tyr yield was 60% higher than e ‐ aq attributed to splitting of the phenolic bond. Computer analysis of e ‐ aq and Tyr decays for Tyr indicates the importance of electron‐radical recombination in competition with electron scavenging and bimolecular radical‐radical reactions. Evidence for intramolecular electron migration has been obtained in cystinyl‐bis‐Tyr.