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CHEMICAL REACTION RATES OF AMINO ACIDS WITH SINGLET OXYGEN
Author(s) -
Matheson I. B. C.,
Lee John
Publication year - 1979
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.1751-1097.1979.tb07786.x
Subject(s) - singlet oxygen , histidine , chemistry , tryptophan , alanine , reaction rate constant , amino acid , quenching (fluorescence) , oxygen , chemical reaction , methionine , photochemistry , tyrosine , phenylalanine , fluorescence , organic chemistry , biochemistry , kinetics , physics , quantum mechanics
— The chemical reactions of amino acids with singlet oxygen have been measured in D 2 O solution where the singlet oxygen was generated directly by irradiation of the oxygen 3 ∑ g ‐ → 1 δ g + lv electronic transaction with the 1.06 μm output of an Nd‐Yag laser. Chemical reaction was measured as amino acid loss by an amino acid analyzer or by fluorescence in the cases of tryptophan and tyrosine. The chemical rate constants, in units of 10 7 M ‐1 s ‐1 , are histidine 10, tryptophan 3, methionine 1.7, tyrosine 0.8 and alanine 0.2, In the cases of histidine, methionine and alanine the interaction appears to be entirely chemical, i.e. there is no evidence for physical quenching in addition to the chemical reaction. The histidine chemical reaction rate constant shows an increase with pD with a p K of 6.9.