Mode of Action of the Toxin from Pseudomonas phaseolicola: II. Mechanism of Inhibition of Bean Ornithine Carbamoyltransferase 12
AUTOR(ES)
Tam, Leslie Q.
RESUMO
A chlorosis-inducing toxin of Pseudomonas phaseolicola was examined for inhibition of ornithine carbamoyltransferease prepared from acetone powder of bean (Phaseolus vulgaris L.) plants. The enzyme has a pH optimum at 8.5, involves a ternary complex reaction mechanism, and shows Michaelis constants of 5.0 mm and 1.7 mm for ornithine and carbamoylphosphate, respectively. Assuming reversible catalysis, Michaelas constants of 11 mm and 3.3 mm are calculated for citrulline and arsenate. Toxin induces allosteric competitive inhibition in relation to carbamoylphosphate and a noncompetitive mode of inhibition in relation to ornithine, except at high toxin concentrations where uncompetitive inhibition is observed. In the backward assay, competitive inhibition is observed for both arsenate and citrulline. Inhibition is increased with preincubation time and shows saturation kinetics with regard to toxin concentration.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=366057Documentos Relacionados
- Mode of Action of the Toxin from Pseudomonas phaseolicola: I. Toxin Specificity, Chlorosis, and Ornithine Accumulation 12
- Phaseolotoxin-insensitive ornithine carbamoyltransferase of Pseudomonas syringae pv. phaseolicola: basis for immunity to phaseolotoxin.
- Inhibition of Ornithin Carbamyl Transferase from Bean Plants by the Toxin of Pseudomonas phaseolicola1
- Ornithine carbamoyltransferase genes and phaseolotoxin immunity in Pseudomonas syringae pv. phaseolicola
- Integration and excision of pMC7105 in Pseudomonas syringae pv. phaseolicola: involvement of repetitive sequences.