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

Autor(es)

Ramos, Luiz D. ^[1] ; Prado, Fernanda M. ^[2] ; Stevani, V, Cassius ; Di Mascio, Paolo ^[2] ; Bechara, Etelvino J. H. ^[3]

Afiliação do(s) autor(es)

^[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

• Tipo de documento: Artigo Científico
• Fonte: Photochemistry and Photobiology; v. 97, n. 2 FEB 2021.
• Citações Web of Science: 1

Resumo

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)

• Processo FAPESP: 12/12663-1 - Oxigênio singlete e peróxidos em química biológica
• Beneficiário: Paolo Di Mascio
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 19/24515-6 - Fontes, alvos e respostas biológicas de espécies tripletes e oxigênio singlete: patogenicidade e supressão
• Beneficiário: Luiz Duarte Ramos
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 17/22501-2 - Quimiexcitação eletrônica em sistemas biológicos: bioluminescência e 'foto'química no escuro
• Beneficiário: Etelvino José Henriques Bechara
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 13/07937-8 - Redoxoma
• Beneficiário: Ohara Augusto
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs