Biochemical characterization of a novel hydantoin racemase from Agrobacterium tumefaciens C58
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Martínez Rodríguez, Sergio; Las Heras Vázquez, Francisco Javier; Clemente Jiménez, Josefa María; Rodríguez Vico, FelipeFecha
2004Resumen
A novel hydantoin racemase gene of Agrobacterium tumefaciens C58 (AthyuA2) has been cloned and expressed in Escherichia coli BL21.
The recombinant protein was purified in a one-step procedure and showed an apparent molecular mass of 27,000 Da in SDS-gel
electrophoresis. Size exclusion chromatography analysis determined a molecular mass of approximately 100,000 Da, suggesting that the
native enzyme is a tetramer. The optimum pH and temperature for hydantoin racemase activity were 7.5 and 55 °C, respectively, with
L-5-ethylhydantoin as substrate. Enzyme activity was strongly inhibited by Cu2+ and Hg2+. No effect on enzyme activity was detected with any other divalent cations, EDTA or DTT, suggesting that it is not a metalloenzyme. Kinetic studies showed the preference of the enzyme for hydantoins with short rather than long aliphatic side chains or hydantoins with aromatic rings.
Palabra/s clave
Racemization
D-amino acid
Hydantoin racemase 2
Purification