Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0008272 (chlorosis)
 2,195 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Mode of Action of the Toxin from Pseudomonas phaseolicola: II. Mechanism of Inhibition of Bean Ornithine Carbamoyltransferase. 1665 53

The ethyl acetate extract of the conidia germination fluid from an Avena isolate (Br58) of Pyricularia oryzae had chlorosis-inducing activity on oat leaf segments. The same activity was also present in the acetone extract of an oatmeal agar culture of Br58. Fungal cultures were used for a large-scale preparation. A series of acetone and ethyl acetate extraction monitored by chromatography was used to isolate an active fraction. The active principle was purified by HPLC. We show by NMR and LC/MS that the toxin was an oxidized C18 unsaturated fatty acid named Mag-toxin. Mag-toxin induced chlorosis on oat leaf segments incubated in the light but not in the dark. Reactive oxygen species (ROS) and cell death were induced by Mag-toxin in oat cells. The sub-cellular localization of ROS generation induced by the toxin treatment was correlated with the location of mitochondria. Interestingly, the induction of ROS generation and cell death by Mag-toxin was light-independent.
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PMID:Induction of chlorosis, ROs generation and cell death by a toxin isolated from Pyricularia oryzae. 2107 40