INVESTIGADORES
CECCARELLI Eduardo Augusto
congresos y reuniones científicas
Título:
Modulation Of The Enzyme Catalytic Efficiency By Amino Acid Volume
Autor/es:
MUSUMECI, MATIAS M.; RIAL, D; CATALANO DUPUY, D; ARAKAKI, A; CECCARELLI, EDUARDO AUGUSTO
Lugar:
Pinamar, Argentina
Reunión:
Congreso; 10th Congress Panamerican Association for Biochemistry and Molecular Biology; 2005
Institución organizadora:
SAIB - PABMB
Resumen:
Ferredoxin-NADP(H)
reductases (FNR) are ubiquitous flavoenzymes that participate in a broad range of redox metabolic pathways. Several
structural features of these enzymes remain yet to be explained. FNRs consist of two domains; one
involved in the binding of the prosthetic group FAD and the other in the
binding of NADP. The
residue Y308 in pea FNR is stacked near parallel to the re-face of the flavin and is highly conserved among members of the
family. Computing
the relative free energy for the lumiflavin-phenol pair with the relative
positions found for Y308 in pea FNR we have concluded that this amino acid is
constrained against the isoalloxazine. This effect is probably performed by
amino acids C266 and L268, which are facing the other side of this tyrosine,
forcing it to adopt a more planar orientation with respect to the flavin. Simple and double FNR mutants
of amino acids C266 and L268 were obtained and characterized. We observed that
reducing amino acid volume decreases the catalytic efficiency without altering
the protein structure, probably due to an increase of the Y308 - isoalloxazine interaction. Our results
allows to suggest that these amino acids have been evolutively selected by
volume and that they participate in the fine tuning of the enzyme efficiency,
modulating the interaction of the Y308 with the isoalloxazine.