Identification of phenolic compounds in isolated vacuoles of the medicinal plant Catharanthus roseus and their interaction with vacuolar class III peroxidase: an H2O2 affair?

• Tipo: Artigo em Revista Científica Internacional
• Data: 2011

Autores

Federico Ferreres (Autor) Outra; Raquel Figueiredo (Autor) Outra; Sara Bettencourt (Autor) Outra; Ines Carqueijeiro (Autor) Outra; Juliana Oliveira (Autor) Outra; Angel Gil Izquierdo (Autor) Outra; David M Pereira (Autor) Outra; Patricia Valentao (Autor) FFUP; Paula B Andrade (Autor) FFUP; Patricia Duarte (Autor) Outra; Alfonso R Ros Barcelo (Autor) Outra; Mariana Sottomayor (Autor) FCUP

Revista

Título: Journal of Experimental Botany

Vol. 62

Páginas: 2841-2854

ISSN: 0022-0957

Editora: Oxford University Press

Indexação

ISI Web of Knowledge - 130 Citações

Scopus - 148 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Ciências biológicas

Outras Informações

ID Authenticus: P-002-RRR

DOI: 10.1093/jxb/erq458

Abstract (EN): Class III peroxidases (Prxs) are plant enzymes capable of using H2O2 to oxidize a range of plant secondary metabolites, notably phenolic compounds. These enzymes are localized in the cell wall or in the vacuole, which is a target for secondary metabolite accumulation, but very little is known about the function of vacuolar Prxs. Here, the physiological role of the main leaf vacuolar Prx of the medicinal plant Catharanthus roseus, CrPrx1, was further investigated namely by studying its capacity to oxidize co-localized phenolic substrates at the expense of H2O2. LC-PAD-MS analysis of the phenols from isolated leaf vacuoles detected the presence of three caffeoylquinic acids and four flavonoids in this organelle. These phenols or similar compounds were shown to be good CrPrx1 substrates, and the CrPrx1-mediated oxidation of 5-O-caffeoylquinic acid was shown to form a co-operative regenerating cycle with ascorbic acid. Interestingly, more than 90% of total leaf Prx activity was localized in the vacuoles, associated to discrete spots of the tonoplast. Prx activity inside the vacuoles was estimated to be 1809 nkat ml(-1), which, together with the determined concentrations for the putative vacuolar phenolic substrates, indicate a very high H2O2 scavenging capacity, up to 9 mM s(-1). Accordingly, high light conditions, known to increase H2O2 production, induced both phenols and Prx levels. Therefore, it is proposed that the vacuolar couple Prx/secondary metabolites represent an important sink/buffer of H2O2 in green plant cells.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 14