IAL   21557
INSTITUTO DE AGROBIOTECNOLOGIA DEL LITORAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
FUNCTIONAL CHARACTERIZATION OF PROTEINS INVOLVED IN A THIOREDOXIN SYSTEM OPERATING IN PEACH FRUIT
Autor/es:
M.D. HARTMAN; D.G. ARIAS; N. SASONI; C.M. FIGUEROA; A.A. IGLESIAS
Lugar:
Rosario
Reunión:
Congreso; Sociedad Argentina de Investigaciones Bioquímicas; 2014
Resumen:
Redox regulation plays a significant role in a wide range of biological processes. Thus, in order to maintain redox equilibrium, cells have developed many compartmentalized enzymatic antioxidant systems. NADPH-dependent thioredoxin reductases (NTRs) are regulatory enzymes determining the redox state of thioredoxins (TRXs): once reduced, TRX is able to reduce target proteins. We cloned the genes coding for NTR (PpeNTR) and cytosolic TRX (PpeTRXh) in peach fruit and purified the recombinant proteins. PpeNTR was unable to directly reduce the chemical DTNB, but in presence of recombinant PpeTRXh the system was fully active (with a maximum at pH 7.5). Interestingly, NADPH and NADH were used as electron donor with a similar catalytic efficiency. PpeNTR showed a high catalytic efficiency for reducing the homologous PpeTRXh but the ability to reduce the ortholog E. coli NTR was significantly lower. The capacity of PpeNTR to catalyze the reversible transference of reduction equivalents from NADPH to oxidized TRX was utilized to determine the reduction potential of the enzyme at −296 mV. There is a thermodynamic coherence between the calculated reduction potential of PpeNTR, the corresponding potential for NAD(P)H (−320 mV), and PpeTRXh (−265 mV), which is indicative of the potential physiological operation of the system for the transference of reduction equivalents in plants.