35169-97-2Relevant academic research and scientific papers
Mechanism of Dye-sensitized Photooxidation of Tryptophan, Tryptamine, and Their Derivatives. Singlet Oxygen Process in Competition with Type I Process
Inoue, Kenzo,Matsuura, Teruo,Saito, Isao
, p. 2959 - 2964 (1982)
Photosensitized oxidation of tryptophan (Trp), tryptamine, and their derivatives were inestigated with a variety of sensitizers.Rose Bengal sensitized photooxidations proceed exclusively via Type II mechanism (singlet oxygen mechanism), whereas for thionine-sensitized photooxidations both Type I (nonsinglet oxygen mechanisms) and Type II mechanisms are operative under a given set of conditions.Rate constants of reaction, in units of 106 M-1s-1, were determined to be 3 for Trp, 4 for tryptophan methyl ester, 4 for Nb-acetyltryptophan methyl ester, 9 for tryptamine, and 7 for Nb-methoxycarbonyltryptamine in the Rose Bengal-sensitized photooxidations.These values are in good agreement with those obtained from reactions with chemically generated singlet oxygen.Quenching rate constants are somewhat larger than reaction rates constants, indicating that the quenching process is the major path for the interaction of singlet oxygen with these indolic substrates.Oxidation products in chemically generated singlet-oxygen reaction of Trp are compared with those obtained from dye-sensitized photooxidations.
The mechanism of formation of N -formylkynurenine by heme dioxygenases
Basran, Jaswir,Efimov, Igor,Chauhan, Nishma,Thackray, Sarah J.,Krupa, James L.,Eaton, Graham,Griffith, Gerry A.,Mowat, Christopher G.,Handa, Sandeep,Raven, Emma Lloyd
experimental part, p. 16251 - 16257 (2011/12/02)
Heme dioxygenases catalyze the oxidation of l-tryptophan to N-formylkynurenine (NFK), the first and rate-limiting step in tryptophan catabolism. Although recent progress has been made on early stages in the mechanism, there is currently no experimental data on the mechanism of product (NFK) formation. In this work, we have used mass spectrometry to examine product formation in a number of dioxygenases. In addition to NFK formation (m/z = 237), the data identify a species (m/z = 221) that is consistent with insertion of a single atom of oxygen into the substrate during O2-driven turnover. The fragmentation pattern for this m/z = 221 species is consistent with a cyclic amino acetal structure; independent chemical synthesis of the 3a-hydroxypyrroloindole-2-carboxylic acid compound is in agreement with this assignment. Labeling experiments with 18O2 confirm the origin of the oxygen atom as arising from O2-dependent turnover. These data suggest that the dioxygenases use a ring-opening mechanism during NFK formation, rather than Criegee or dioxetane mechanisms as previously proposed.
DYE-SENSITIZED PHOTO-OXYGENATION OF TRYPTOPHAN
Nakagawa, Masako,Yokoyama, Yukio,Kato, Shiro,Hino, Tohru
, p. 2125 - 2132 (2007/10/02)
Dye-sensitized photo-oxygenation of L-triptophan (1) has been studied at various pH and in various buffers.Disappearance of 1 in both acetate and phosphate buffers was rapid at higher pH.The tricyclic hydroperoxide (8) was the sole product in the oxidatio
OXIDATIVE TRANSFORMATION OF TRYPTOPHAN TO 5-HYDROXY-N-FORMYLKYNURENINE
Nakagawa, Masako,Yokoyama, Yukio,Kato, Shiro,Hino, Tohru
, p. 59 - 62 (2007/10/02)
Dye-sensitized photooxygenation of L-tryptophan in an alkaline phosphate buffer followed by NaBH4 reduction afforded 3a,5-dihydroxypyrroloindole 5 which readily underwent air oxidation to give 5-hydroxy-N-formylkynurenine 6a.
DYE-SENSITIZED PHOTOOXYGENATION OF TRYPTOPHAN: 3a-HYDROPEROXYPYRROLOINDOLE AS A LABILE PRECURSOR OF FORMYLKYNURENINE
Nakagava, Masako,Kato, Shiro,Kataoka, Shigehiro,Kodato, Shinichi,Watanabe, Hideyuki,et al.
, p. 1013 - 1026 (2007/10/02)
The isolation, structure determination, and reactivity of the tricyclic labile hydroperoxides 10 and 2 obtained by dye-sensitized photooxygenation of L-, D-, and DL-tryptophan and Nb-methoxycarbonyltryptophan ester are reported.The tricyclic hydroperoxide 10, under apprpopiate conditions, was easily convertible to formylkynurenine.Plausible mechanisms for these transformations are discussed.Keywords-tryptophan and its derivatives; dye-sensitized photooxygenation; formylkynurenine; hydroperoxypyrroloindoles; 3-hydroperoxyindolenines; 1,3-benzoxazines; CD spectra; rearrangement; ring-chain tautomerism; biological oxidation
Dye-sensitized Photo-oxygenation of Tryptophan to give N'-Formylkynurenine
Nakagawa, Masako,Kato, Shiro,Nakano, Kumiko,Hino, Tohru
, p. 855 - 856 (2007/10/02)
Exclusive conversion of the tricyclic hydroperoxide (1) into N'-formylkynurenine (2) has been found to occur in Na2CO3-AcOH (pH 7) and the methylene blue-sensitized photo-oxygenation of tryptophan in the same system has given N'-formylkynurenine as the sole product, in contrast with the reaction in water, which gave compound (1).
