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Query: UNIPROT:P04040 (Catalase)
 3,577 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lactobacillus plantarum (ATCC 8014) cells, grown aerobically on glucose medium, consumed molecular oxygen when incubated with either glucose, D/L-lactate or pyruvate as substrate. Cell extracts catalyzed the oxidation of NADH, D/L-lactate of pyruvate with O2. Per mol O2 2mol of NADH were consumed indicating that O2 was reduced to H2O; reduction proceeded via H2O2 involving a NADH oxidase and a NADH peroxidase. Catalase activity was absent. Pyruvate oxidation with O2 led to the formation of H2O2, lactate oxidation to the formation of H2O. Thus in L. plantarum different mechanisms are available by which molecular oxygen can be used as electron acceptor for oxidation reactions.
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PMID:Oxygen utilization by Lactobacillus plantarum. I. Oxygen consuming reactions. 737 4

We have found previously that astrocytes can provide cysteine to neurons. However, cysteine has been reported to be neurotoxic although it plays a pivotal role in regulating intracellular levels of glutathione, the major cellular antioxidant. Here, we show that cysteine toxicity is a result of hydroxyl radicals generated during cysteine autoxidation. Transition metal ions are candidates to catalyze this process. Copper substantially accelerates the autoxidation rate of cysteine even at submicromolar levels, whereas iron and other transition metal ions, including manganese, chromium, and zinc, are less efficient. The autoxidation rate of cysteine in rat CSF is equal to that observed in the presence of approximately 0.2 microm copper. In tissue culture tests, we found that cysteine toxicity depends highly on its autoxidation rate and on the total amount of cysteine being oxidized, suggesting that the toxicity can be attributed to the free radicals produced from cysteine autoxidation, but not to cysteine itself. We have also explored the in vivo mechanisms that protect against cysteine toxicity. Catalase and pyruvate were each found to inhibit the production of hydroxyl radicals generated by cysteine autoxidation. In tissue culture, they both protected primary neurons against cysteine toxicity catalyzed by copper. This protection is attributed to their ability to react with hydrogen peroxide, preventing the formation of hydroxyl radicals. Pyruvate, but not catalase or glutathione peroxidase, was detected in astrocyte-conditioned medium and CSF. Our data therefore suggest that astrocytes can prevent cysteine toxicity by releasing pyruvate.
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PMID:Pyruvate released by astrocytes protects neurons from copper-catalyzed cysteine neurotoxicity. 1133 61