Glutathione Reductase from Phaeodactylum tricornutum: Purification and Characterization

D.G. ARIAS, V. MÁRQUEZ, A. BECCARIA, S.A. GUERRERO, A.A. IGLESIAS

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunión Anual de SAIB; 2007

SAIB

EN-P18.GLUTATHIONE REDUCTASE FROM PHAEODACTYLUM T R I C O R N U T U M: P U R I F I C AT I O N A N D CHARACTERIZATIONArias DG, MárquezV, Beccaria AJ, Guerrero SA, Iglesias AA.UNL-CONICET, Fac Bioquímica y Ciencias Biológicas, 3000Santa Fe. E-mail: darias@fbcb.unl.edu.arP.tricornutum KP.tricornutumGranted by UNL, CAI+D 2006; ANPCyT, PICT´03 01-14733,PAV´03 137.The cellular redox state is a crucial mediator of multiple metabolic,signalling and transcriptional processes in the cells. Glutathione(GSH) is a widely distributed low molecular weight thiol, whichprovides reducing equivalents to the cell under conditions ofoxidative stress, being oxidized to glutathione disulfide (GSSG) inthe process. The enzyme glutathione reductase, a member ofpyridine nucleotide-disulfide oxidereductase family, uses thereducing power of NADPH to regenerate GSH from GSSG.Diatoms, brown unicellular algae, are important components ofmarine phytoplankton, being particularly relevant for geochemicalcycling of minerals, and global carbon fixation.As a consequence oftheir importance in the global ecosystem, their ecology andphysiology have been the focus of research. In this work, a putativeglutathione reductase was purified from cellular extracts ofand functional characterized. The m value forNADPH and GSSG were 14 and 32 M, respectively. The enzymewas specific for NADPH but not for NADH as electron donor. Theenzyme activity was markedly inhibited by metal ions such as Cu ,Zn , Co and Ni . The activity was maximum at pH 8.0 and 32ºC.Our results strongly support the occurrence of the GSH system in, which was poorly described in this diatom.