Euglena gracilis: Biochemical properties of a membrane bound ecto-phosphatase activity modulated by fluoroaluminate complexes and different trophic conditions.

Autor: Freitas-Mesquita AL; Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil. Electronic address: anita@bioqmed.ufrj.br., Carvalho-Kelly LF; Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil., Majerowicz TSS; Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Rua Senador Furtado, 121. Maracanã, Rio de Janeiro, RJ 20270-021, Brazil., Meyer-Fernandes JR; Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil. Electronic address: meyer@bioqmed.ufrj.br.
Jazyk: angličtina
Zdroj: European journal of protistology [Eur J Protistol] 2023 Aug; Vol. 90, pp. 126010. Date of Electronic Publication: 2023 Jul 20.
DOI: 10.1016/j.ejop.2023.126010
Abstrakt: The ecto-phosphatases belong to a group of enzymes closely associated with the cell surface that has its catalytic site facing the extracellular environment, where different phosphorylated substrates can be hydrolyzed. In the present work, we biochemically characterized the ecto-phosphatase activity of the freshwater microalgae Euglena gracilis, a model microorganism, ubiquitously distributed and resistant to several environmental stressors. The ecto-phosphatase activity is acidic, stimulated by copper and presents the following apparent kinetic parameters: K m  = 2.52 ± 0.12 mM p-NPP and V max  = 3.62 ± 0.06 nmol p-NP × h -1  × 10 6 cells. We observed that zinc, orthovanadate, molybdate, fluoride, and inorganic phosphate inhibit the ecto-phosphatase activity with different magnitudes. Fluoroaluminate complexes are also inhibitors of this ecto-phosphatase activity. They can be formed in the enzyme reaction conditions and are likely to occur in a natural environment where E. gracilis can be found. The ecto-phosphatase activity is constant through the culture growth phases and is negatively modulated after continuous subculturing in the dark when a shift from phototrophic to the heterotrophic metabolism is likely. The analysis of those biochemical parameters may contribute to understanding the role of E. gracilis ecto-phosphatase activity in natural environments.
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Databáze: MEDLINE
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