TAILIEUCHUNG - Báo cáo khoa học: Modulation of the enzymatic efficiency of ferredoxin-NADP(H) reductase by the amino acid volume around the catalytic site

Ferredoxin (flavodoxin)-NADP(H) reductases (FNRs) are ubiquitous flavoenzymes that deliver NADPH or low-potential one-electron donors (ferredoxin, flavodoxin, adrenodoxin) to redox-based metabolic reactions in plastids, mitochondria and bacteria. Plastidic FNRs are quite efficient reductases. | ễFEBS Journal Modulation of the enzymatic efficiency of ferredoxin-NADP H reductase by the amino acid volume around the catalytic site Matias A. Musumeci Adrian K. Arakaki Daniela V. Rial Daniela L. Catalano-Dupuy and Eduardo A. Ceccarelli Molecular Biology Division Instituto de Biologia Molecular y Celular de Rosario IBR Facultad de Ciencias Bioquimicas y Farmaceuticas Universidad Nacionalde Rosario Argentina Keywords catalytic efficiency enzyme evolution ferredoxin ferredoxin-NADP H reductase oxidoreductases Correspondence E. A. Ceccarelli Molecular Biology Division Instituto de Biologia Molecular y Celular de Rosario IBR CONICET Facultad de Ciencias Bioquimicas y Farmaceuticas Universidad Nacionalde Rosario Suipacha 531 S2002LRK Rosario Argentina Fax 54 341 4390465 Tel 54 341 4351235 E-mail ceccarelli@ Received 1 November 2007 revised 8 January 2008 accepted 16 January 2008 doi Ferredoxin flavodoxin -NADP H reductases FNRs are ubiquitous flavoenzymes that deliver NADPH or low-potential one-electron donors ferredoxin flavodoxin adrenodoxin to redox-based metabolic reactions in plastids mitochondria and bacteria. Plastidic FNRs are quite efficient reductases. In contrast FNRs from organisms possessing a heterotrophic metabolism or anoxygenic photosynthesis display turnover numbers 20- to 100-fold lower than those of their plastidic and cyanobacterial counterparts. Several structural features of these enzymes have yet to be explained. The residue Y308 in pea FNR is stacked nearly parallel to the re-face of the flavin and is highly conserved amongst members of the family. By computing the relative free energy for the lumiflavin-phenol pair at different angles with the relative position found for Y308 in pea FNR it can be concluded that this amino acid is constrained against the isoalloxazine. This effect is probably caused by amino acids C266 and L268 which face the other side of this tyrosine. Simple and double FNR mutants

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