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QUENCHING OF TRYPTOPHAN PHOSPHORESCENCE IN ALCOHOL DEHYDROGENASE FROM HORSE LIVER and ITS TEMPERATURE DEPENDENCE
Author(s) -
Barboy Natalie,
Feitelson Jehuda
Publication year - 1985
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.1751-1097.1985.tb03440.x
Subject(s) - phosphorescence , chemistry , quenching (fluorescence) , activation energy , arrhenius equation , tryptophan , alcohol dehydrogenase , photochemistry , arrhenius plot , alcohol , fluorescence , organic chemistry , biochemistry , physics , amino acid , quantum mechanics
— The phosphorescence of alcohol dehydrogenase from horse liver (LADH) can be observed at room temperature. The quenching of this long‐lived light emission, which comes from a tryptophan residue well buried within the interior of the enzyme structure, was measured. The rate constants for the quenching by the small oxygen molecule and by the I ‐1 ion were found to be 1.4 → 10 8 M ‐1 s ‐1 and 10 8 M ‐1 s ‐1 , respectively, at room temperature. The temperature dependence of the quenching yields an activation energy of about 14 kcal/mol. This activation energy and the meaning of the accompanying large pre‐exponential factor in the Arrhenius equation, A = 10 18 M ‐l s ‐1 , are discussed in terms of a model in which the quencher threads its way through the protein network.