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Acid phosphatase from maize scutellum: Negative cooperativity suppression by glucose
Authors:Mario S. Palma  Alice M. Teno  Antonio Rossi
Affiliation:Departamento de Química, FFCLRP-USP, 14.100 Ribeirào Preto, SP, Brazil
Abstract:Acid phosphatase purified from maize scutellum, upon acylation with succinic anhydride, still shows negative co-operativity for the hydrolysis of glucose-6-phosphate at pH 5.4. This phenomenon is abolished by glucose, for both native and succinylated enzymes, through stimulation of the initial velocities at sub-optimal substrate concentrations. However, negative co-operativity for the enzymatic hydrolysis of p-nitrophenylphosphate at pH 5.4 is suppressed only at high concentrations of glucose. Furthermore, the hydrolysis of p-nitrophenylphosphate is noncompetitively inhibited (low affinity form of the enzyme molecule) by glucose, which suggests the existence of different substrate binding sites.
Keywords:Gramineae  maize  scutellum  germination  acid phosphatase  negative co-operativity.
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