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|Type:||Artigo de periódico|
|Title:||Catabolism of caffeine and purification of a xanthine oxidase responsible for methyluric acids production in Pseudomonas putida L|
|Abstract:||Caffeine catabolism and a xanthine oxidase involved in the alkaloid breakdown were studied in Pseudomonas putida L, a strain displaying high ability to grow on this substrate. Cells cultured with unlabelled caffeine and C-14 labeled caffeine and xanthine showed that this alkaloid was broken-down via theobromine/paraxanthine -> 7-methylxanthine -> xanthine -> uric acid -> allantoin -> allantoic acid. Methyluric acids were formed from the oxidation of theobromine, paraxanthine and 7-methylxanthine, although no bacterial growth was observed on these compounds, indicating that this might be due to a wide substrate specificity of xanthine oxidase. This was confirmed by activity staining in PAGE where activity was observed with theophylline and 3-methylxanthine, which are not involved in the alkaloid breakdown. A single band of activity was detected without addition of NAD(+), showing an oxidase form of the enzyme. The enzyme optimum temperature and pH were 30 degrees C and 7.0, respectively. The determined K-m was 169 mu M, and the pi 3.1-4.0. The molecular weight determined by side by side comparison of activity staining of the enzyme in PAGE and PAGE of BSA was 192 kDa, which was coincident with the sum (198.4 kDa) of three subunits (71, 65.6 and 61.8 kDa) of the purified protein.|
|Editor:||Soc Brasileira Microbiologia|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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