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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

l-Tryptophan Interactions with the Horseradish Peroxidase-Catalyzed Generation of Triplet Acetone

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Ramos, Luiz D. [1] ; Prado, Fernanda M. [2] ; Stevani, V, Cassius ; Di Mascio, Paolo [2] ; Bechara, Etelvino J. H. [3]
Total Authors: 5
[1] Univ Sao Paulo, Dept Quim Fundamental, Inst Quim, Sao Paulo, SP - Brazil
[2] Univ Sao Paulo, Inst Quim, Dept Bioquim, Sao Paulo, SP - Brazil
[3] Stevani, Cassius, V, Univ Sao Paulo, Dept Quim Fundamental, Inst Quim, Sao Paulo, SP - Brazil
Total Affiliations: 3
Document type: Journal article
Source: Photochemistry and Photobiology; v. 97, n. 2 FEB 2021.
Web of Science Citations: 1

Triplet carbonyls generated by chemiexcitation are involved in typical photobiochemical processes in the absence of light. Due to their biradical nature, ultraweak light emission and long lifetime, electronically excited triplet species display typical radical reactions such as isomerization, fragmentation, cycloaddition and hydrogen abstraction. In this paper, we report chemical reactions in a set of amino acid residues induced by the isobutanal/horseradish peroxidase (IBAL/HRP) system, a well-known source of excited triplet acetone (Ac-3{*}). Accordingly, quenching of Ac-3{*} by tryptophan (Trp) unveiled parallel enzyme damage and inactivation, likely explained by scavenging of IBAL tertiary radical reaction intermediate and Ac-3{*}-derived 2-hydroxy-i-propyl radical. Quenching constants were calculated from Stern-Volmer plots, and the structure of radical adducts was revealed by mass spectrometry. As expected, a concurrent Schiff-type adduct was found to be one of the reaction by-products. These findings draw attention to potential structural and functional changes in enzymes involved in the electronic chemiexcitation of their products. (AU)

FAPESP's process: 12/12663-1 - Singlet molecular oxygen and peroxides in chemical biology
Grantee:Paolo Di Mascio
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 19/24515-6 - Sources, targets and biological responses of triplet species and singlet oxygen: pathogenicity and quenching
Grantee:Luiz Duarte Ramos
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 17/22501-2 - Electronic chemiexcitation in biological systems: bioluminescence and photochemistry in the dark
Grantee:Etelvino José Henriques Bechara
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 13/07937-8 - Redoxome - Redox Processes in Biomedicine
Grantee:Ohara Augusto
Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC