The hydroxylation of tryptophan

Maskos, Zofia; Rush, J. D.; Koppenol, Willem H.

doi:10.1016/0003-9861(92)90605-v

Cited by 104 publications

(73 citation statements)

References 27 publications

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“…The same process seems to occur with tryptophan, since Mason and coworkers [31] and Minetti and coworkers [26] demonstrated the formation of tryptophan centred radical in proteins under oxidative conditions. Also, formation of a dimer and polymers of tryptophan under oxidative conditions was mentioned by Maskos et al [23], although the compounds structures were not identified. The formation of the dimer cross-linking Trp-Trp should occur between two Trp radicals, probably at the C3 carbon [26] or C6 carbon [31] of the indole ring, as inferred previously.…”

Section: Resultsmentioning

confidence: 97%

“…These studies have identified the principal oxidation products of Trp, 2-, 4-, 5-, 6-, 7-hydroxyl derivatives and N-formylkynurenine, and some other less representative species. Several other observed oxidation products haven't been identified by the methods used in the monitoring of these reactions, specially when UV or fluorescence were used to detect and identify the final products of oxidation [23,25]. To our knowledge, the detection of tryptophan radicals formed by oxidation reactions, other than in proteins using MS, has not been reported.…”

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confidence: 99%

“…Tryptophan oxidation by hydroxyl radical formed either by Fenton reaction or radiolysis has already been studied [23][24][25]. However, none of these studies included a complete characterization of the oxidation products.…”

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confidence: 99%

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Identification of oxidation products and free radicals of tryptophan by mass spectrometry

Domingues

Reis

et al. 2003

J. Am. Soc. Mass Spectrom.

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New oxidation products and free radicals derived from tryptophan (Trp) oxidation under Fenton reaction conditions were identified using mass spectrometry. After the oxidation of tryptophan using hydrogen peroxide and iron (II) system (Fenton reaction), mono-and dihydoxy tryptophans and N-formylkynurenine were identified using electrospray mass spectrometry (ES-MS) and ES-MS/MS. Besides these products, new products resulting from the reaction of tryptophan and oxidized tryptophan and 3-methyl indole derivatives were also identified. The 3-methyl indole derivatives resulted, most probably, from the oxidation process and not from in-source processes. A dimer formed by cross-linking between two Trp radicals (Trp-Trp), similar to the previously described tyrosine dimer was observed, as well as the corresponding monohydroxy-dimer (Trp-Trp-OH). Tandem mass spectrometry was used to identify the structures of these new oxidation products. Free radicals derived from tryptophan oxidation under Fenton reaction were detected using as spin trap the DMPO. The free radical species originated during the oxidation reaction formed stable adducts with the spin trap, and these adducts were identified by ES-MS. New adducts of oxidized tryptophan radicals, namely monohydroxy-tryptophan and dihydroxy-Trp dimer radicals, with one and two DMPO spin trap molecules where identified. Tandem mass spectrometry was used to confirm the proposed structure of the observed adducts. (J

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Section: Resultsmentioning

confidence: 97%

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confidence: 99%

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Identification of oxidation products and free radicals of tryptophan by mass spectrometry

Domingues

Reis

et al. 2003

J. Am. Soc. Mass Spectrom.

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“…A more plausible explanation for the regioselective oxidation is that Trp L163 is located in close proximity to where the short-lived intermediates are generated. Under aerobic conditions in solution, it is known that ''hydroxylradical-mediated'' hydroxylation of tryptophan leads to a mixture of 4-, 5-, 6-, and 7-hydroxy tryptophan in addition to N-formylkynurenine (NFK) (14).…”

Section: Resultsmentioning

confidence: 99%

Evidence for the production of trioxygen species during antibody-catalyzed chemical modification of antigens

Wentworth

Zhu

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

115

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Recent work in our laboratory showed that products formed by the antibody-catalyzed water-oxidation pathway can kill bacteria. Dihydrogen peroxide, the end product of this pathway, was found to be necessary, but not sufficient, for the observed efficiency of bacterial killing. The search for further bactericidal agents that might be formed along the pathway led to the recognition of an oxidant that, in its interaction with chemical probes, showed the chemical signature of ozone. Here we report that the antibodycatalyzed water-oxidation process is capable of regioselectively converting antibody-bound benzoic acid into para-hydroxy benzoic acid as well as regioselectively hydroxylating the 4-position of the phenyl ring of a single tryptophan residue located in the antibody molecule. We view the occurrence of these highly selective chemical reactions as evidence for the formation of a shortlived hydroxylating radical species within the antibody molecule. In line with our previously presented hypothesis according to which the singlet-oxygen ( 1 O* 2) induced antibody-catalyzed wateroxidation pathways proceeds via the formation of dihydrogen trioxide (H 2O3), we now consider the possibility that the hydroxylating species might be the hydrotrioxy radical HO 3• , and we point to the remarkable potential of this either H 2O3-or O3-derivable species to act as a masked hydroxyl radical (HO • ) in a biological environment.

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“…black light, the hydroxyl radicals are believed to attack the double bond in tryptophan (between carbon 2 and 3) and the pyrrol ring will open [49,50]. The superoxide anion will oxidize these to carbon atoms to form NFK (8) [47].…”

Section: The Photo-(catalytic) Conversion Of Tryptophan To Kynureninementioning

confidence: 99%

A Novel Photocatalytic Conversion of Tryptophan to Kynurenine Using Black Light as a Light Source

et al. 2012

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The photocatalytic conversion of an aqueous solution of L-tryptophan (Trp) to kynurenine (KN) was investigated under the illumination of different light sources. Results show that Trp converted to KN with a selectivity of 64% under the illumination of a medium pressure (MP) Hg lamp. KN selectivity was increased to [90% when black light (BL) was used a light source. The novel use of BL in the photocatalytic conversion of Trp to KN significantly reduces the energy consumption compared with MP light.

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The hydroxylation of tryptophan

Cited by 104 publications

References 27 publications

Identification of oxidation products and free radicals of tryptophan by mass spectrometry

Identification of oxidation products and free radicals of tryptophan by mass spectrometry

Evidence for the production of trioxygen species during antibody-catalyzed chemical modification of antigens

A Novel Photocatalytic Conversion of Tryptophan to Kynurenine Using Black Light as a Light Source

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