One-proton catalysis by the α-l-arabinofuranosidase III of Monilinia fructigena
Keyword(s):
1. Michaelis-Menten parameters for the hydrolysis of p-nitrophenyl alpha-L-arabinofuranoside were measured as a function of pL (pH or pD) in both 1H2O and 2H2O. 2. The variation of both Vmax. and Vmax./Km with pL is sigmoid, the pK governing Vmax. shifting from 6.34 +/- 0.05 in 1H2O to 6.84 +/- 0.07 in 2H2O, and that governing Vmax./Km from 5.89 +/- 0.03 in 1H2O to 6.38 +/- 0.05 in 2H2O. 3. In the plateau regions there is a small inverse solvent isotope effect on Vmax./Km (0.92), and one of 1.45 on Vmax. 4. The variation of Vmax. with isotopic composition is strictly linear, indicating that the isotope effect arises from the transfer of a single proton.
1972 ◽
Vol 94
(2)
◽
pp. 573-575
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Keyword(s):
2021 ◽
1971 ◽
Vol 49
(22)
◽
pp. 3665-3670
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2021 ◽
2021 ◽
2021 ◽