Laser flash photolysis of aqueous tryptophan
Laser flash photolysis of aqueous tryptophan at 265 nm generates the neutral radical product of indole ring N-H bond photolysis (lambda/sub max/ 510 nm, 1800 M/sup -1/ cm/sup -1/; 330 nm, 3100 M/sup -1/ cm/sup -1/), the triplet state (lambda/sub max/ 460 nm), and the hydrated electron as initial products. The photoionization quantum yields for tryptophan, 1-methyltryptophan, tyrosine, and glycine-tryptophan peptides have been determined using ferrocyanide as the reference system. The electron and aromatic radical decay by a previously unreported first-order back reaction of 0.80-..mu..sec half-time, leading to residual yields of the separated products after several microseconds significantly smaller than the photoionization yield. The kinetics results are consistent with the formation of a loose complex between the hydrated electron and the radical in which recombination competes with separation. The implications of this process for tryptophyl residue destruction in proteins are considered. A comparable first-order electron decay stage was observed with tryptophan derivatives, tyrosine, I/sup -/, and Fe(CN)/sub 6//sup 4 -/.
- Research Organization:
- Illinois Inst. of Tech., Chicago
- OSTI ID:
- 7211147
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 79:25; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400500* -- Photochemistry
ABSORPTION SPECTRA
AMINO ACIDS
AZOLES
CARBOXYLIC ACIDS
CHEMICAL LASERS
CHEMICAL REACTIONS
DECOMPOSITION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INDOLES
LASERS
LEPTONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PYRROLES
RADICALS
SOLVATED ELECTRONS
SPECTRA
TRYPTOPHAN