Arginine catabolism in Aphanocapsa 6308 |
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Authors: | Pamela J Weathers Heng Leng Chee Mary Mennes Allen |
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Institution: | (1) Department of Biological Sciences, Wellesley College, 02181 Wellesley, MA, USA;(2) Present address: Department of Biology, College of the Holycross, 01610 Worcester, MA, USA |
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Abstract: | The catabolic products of arginine metabolism were observed in Aphanocapsa 6308, a unicellular cyanobacterium, by thin layer chromatography of growth media, by limiting growth conditions, and by enzymatic analysis. Of the organic, nitrogenous compounds examined, only arginine supported growth in CO2-free media. The excretion of ornithine at a concentration level greater than citrulline suggested the existence in Aphanocapsa 6308 of the arginine dihydrolase pathway which produced ornithine, CO2, NH4, + adenosine 5 -triphosphate. Its existence was confirmed by enzymatic analysis. Although cells could not grow on urea as a sole carbon source a very active urease and subsequently an arginase were also demonstrated, indicating that Aphanocapsa can metabolize arginine via the arginase pathway. The level of enzymes for both pathways indicates a lack of genetic control. It is suggested that the arginase pathway provides only nitrogen for the cells whereas the arginine dihydrolase pathway provides not only nitrogen, but also CO2 and adenosine 5 -triphosphate.Nonstandard Abbreviations CCCP
carbonylcyanide mchlorophenyl hydrazone
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethyl urea
- CGP
cyanophycin granule protein
- PS II
photosystem II
- PSI
photosystem I
- TLC
thin layer chromatography
- TCA
trichloroacetic acid
- DPM
disintegrations per min |
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Keywords: | Arginine catabolism Arginine dihydrolase pathway Cyanobacteria Aphanocapsa 6308 Arginase Urease |
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