Fluorescence-quenching mechanism of tryptophan. Remarkably efficient internal proton-induced quenching and charge-transfer quenching
The fluorescence quenching of tyrptophan (Trp) in the absence and presence of 18-crown-6 in CH/sub 3/OH-H/sub 2/ (9:1), vv) mixtures has been studied by means of nanosecond time-resolved single-photon counting, fluorimetry, and photochemical H-D isotope exchange. The fluorescence intensity increases markedly with increasing concentration of 18-crown-6. The quenching can be estimated from the equation k/sub q/ = tau/sub 1//sup 1 -/ - (tau /sub 2//sup max/)/sup -1/, where tau/sub 1/ and tau/sub 1//sup max/ denote the fluorescence lifetimes for free Trp and the 1:1 Trp-18-crown-6 complex, respectively. The internal quenching originates from the electrophilic protonation of the /sup +/NH/sub 3/ group of Trp at the C-4 position of the excited indole ring plus the charge-transfer interaction between the excited indole ring and the ammonium group. The stabilization constant K/sub g/ for the 1:1 complex of Trp with 18-crown-6 has been determined by means of fluorimetry.
- Research Organization:
- Gunma Univ., (Japan)
- OSTI ID:
- 7255990
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 110:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
DEUTERIUM
ISOTOPIC EXCHANGE
HYDROGEN
TRYPTOPHAN
FLUORESCENCE
RADIATIONLESS DECAY
CHEMICAL REACTION KINETICS
EXPERIMENTAL DATA
PHOTOCHEMISTRY
AMINO ACIDS
AROMATICS
AZAARENES
AZOLES
CARBOXYLIC ACIDS
CHEMISTRY
DATA
DE-EXCITATION
ELEMENTS
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN ISOTOPES
INDOLES
INFORMATION
ISOTOPES
KINETICS
LIGHT NUCLEI
LUMINESCENCE
NONMETALS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRROLES
REACTION KINETICS
STABLE ISOTOPES
400500* - Photochemistry