Portal de Periódicos da CAPES

Stereochemistry of the hydrolysis reaction catalyzed by endoglucanase Z from Erwinia chrysanthemi

1992; Wiley; Volume: 300; Issue: 2 Linguagem: Inglês

10.1016/0014-5793(92)80183-h

1873-3468

Frédéric Barras, Isabelle Bortoli‐German, Marielle Bauzan, J. Rouvier, C. Gey, A. Heyraud, Bernard Henrissat,

Carbohydrate Chemistry and Synthesis

Endoglucanase Z from the phytopathogenic bacterium Erwinia chrysanthemi (strain 3937) was purified by affinity chromatography on microcrystalline cellulose Avicel PH101. A kinetic characterization using p-nitrophenyl beta-D-cellobioside and p-nitrophenyl beta-D-lactosde as substrates was conducted: endoglucanase Z exhibited Km values of 3 mM and 7.5 mM and Vm values of 129 and 40 nmol.min-1.mg-1 towards p-nitrophenyl beta-D-cellobioside (kcat = 0.1 s-1) and p-nitrophenyl beta-D-lactoside (kcat = 0.03 s-1), respectively). The hydrolysis of cellotetraitol by endoglucanase Z was followed by HPLC and 1H NMR. Results show that cellobiitol and beta-cellobiose are initially formed, demonstrating that the enzyme is acting by a molecular mechanism retaining the anomeric configuration. This suggests the involvement of a glycosyl-enzyme intermediate.