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Oxidation of melatonin and tryptophan by an HRP cycle involving compound III.
Biochem Biophys Res Commun. 2001 Sep 14; 287(1):130-4.BB

Abstract

We recently described that horseradish peroxidase (HRP) and myeloperoxidase (MPO) catalyze the oxidation of melatonin, forming the respective indole ring-opening product N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) (Biochem. Biophys. Res. Commun. 279, 657-662, 2001). Although the classic peroxidatic enzyme cycle is expected to participate in the oxidation of melatonin, the requirement of a low HRP:H(2)O(2) ratio suggested that other enzyme paths might also be operative. Here we followed the formation of AFMK under two experimental conditions: predominance of HRP compounds I and II or presence of compound III. Although the consumption of substrate is comparable under both conditions, AFMK is formed in significant amounts only when compound III predominates during the reaction. Using tryptophan as substrate, N- formyl-kynurenine is formed in the presence of compound III. Both, melatonin and tryptophan efficiently prevents the formation of p-670, the inactive form of HRP. Since superoxide dismutase (SOD) inhibits the production of AFMK, we proposed that compound III acts as a source of O(-*)(2) or participates directly in the reaction, as in the case of enzyme indoleamine 2,3-dioxygenase.

Authors+Show Affiliations

Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, CEP 05508-900, São Paulo, Brazil.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

11549265

Citation

Ximenes, V F., et al. "Oxidation of Melatonin and Tryptophan By an HRP Cycle Involving Compound III." Biochemical and Biophysical Research Communications, vol. 287, no. 1, 2001, pp. 130-4.
Ximenes VF, Catalani LH, Campa A. Oxidation of melatonin and tryptophan by an HRP cycle involving compound III. Biochem Biophys Res Commun. 2001;287(1):130-4.
Ximenes, V. F., Catalani, L. H., & Campa, A. (2001). Oxidation of melatonin and tryptophan by an HRP cycle involving compound III. Biochemical and Biophysical Research Communications, 287(1), 130-4.
Ximenes VF, Catalani LH, Campa A. Oxidation of Melatonin and Tryptophan By an HRP Cycle Involving Compound III. Biochem Biophys Res Commun. 2001 Sep 14;287(1):130-4. PubMed PMID: 11549265.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Oxidation of melatonin and tryptophan by an HRP cycle involving compound III. AU - Ximenes,V F, AU - Catalani,L H, AU - Campa,A, PY - 2001/9/11/pubmed PY - 2001/10/5/medline PY - 2001/9/11/entrez SP - 130 EP - 4 JF - Biochemical and biophysical research communications JO - Biochem Biophys Res Commun VL - 287 IS - 1 N2 - We recently described that horseradish peroxidase (HRP) and myeloperoxidase (MPO) catalyze the oxidation of melatonin, forming the respective indole ring-opening product N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) (Biochem. Biophys. Res. Commun. 279, 657-662, 2001). Although the classic peroxidatic enzyme cycle is expected to participate in the oxidation of melatonin, the requirement of a low HRP:H(2)O(2) ratio suggested that other enzyme paths might also be operative. Here we followed the formation of AFMK under two experimental conditions: predominance of HRP compounds I and II or presence of compound III. Although the consumption of substrate is comparable under both conditions, AFMK is formed in significant amounts only when compound III predominates during the reaction. Using tryptophan as substrate, N- formyl-kynurenine is formed in the presence of compound III. Both, melatonin and tryptophan efficiently prevents the formation of p-670, the inactive form of HRP. Since superoxide dismutase (SOD) inhibits the production of AFMK, we proposed that compound III acts as a source of O(-*)(2) or participates directly in the reaction, as in the case of enzyme indoleamine 2,3-dioxygenase. SN - 0006-291X UR - https://www.unboundmedicine.com/medline/citation/11549265/Oxidation_of_melatonin_and_tryptophan_by_an_HRP_cycle_involving_compound_III_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0006-291X(01)95557-3 DB - PRIME DP - Unbound Medicine ER -