IBR   13079
INSTITUTO DE BIOLOGIA MOLECULAR Y CELULAR DE ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
MOLECULAR BASIS FOR THE HIGH CATALYTIC
Autor/es:
MUSUMECI, M. M.; CATALANO DUPUY, D. L.; RIAL, D. V.; ARAKAKI, A. K.; CECCARELLI, E. A.
Lugar:
Rosario, Argentina
Reunión:
Congreso; XLII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular 2 al 15 de Noviembre de 2006 - Centro Cultural Parque de España; 2006
Institución organizadora:
Sociedad Argentina de Investigación en Bioquímica y Biología Molecular
Resumen:
FNRs are ubiquitous flavoenzymes that participate in a broadrange of redox metabolic pathways. FNRs consist of twodomains; one involved in the binding of the prosthetic group FADand the other in the binding of NADP+. An aromatic residue(Tyr308 in pea FNR) has been suggested to be responsible forhigh enzyme catalytic efficiency and is conserved in all plant-typeFNRs. Tyr308 stacks coplanar to the re-face of the isoalloxazinemoiety making extensive interactions with it. Analysing single ordouble mutants of aliphatic amino acids facing the other side ofthis Tyr308 by circular dichroism we observed that all mutantswere properly folded. Thermal conformational analysis showedthat increasing the amino acid volume decreases the stability ofthe FNRs mutants. Reducing the amino acid volume producesequally or more stables FNRs than the WT enzyme but, withlower catalytic efficiencies, probably due to an increase of theY308 - isoalloxazine interaction. Our results exemplify how theevolutionary success of enzyme is a compromise between highactivity and high stability and show that in the FNR the volume ofsome aliphatic amino acids have been evolutively selected tomaximize enzyme catalytic efficiency.