L-asparaginase II of saccharomyces cerevisiae. Activity profile during growth using an ure2 mutant P40-3C and a P40-3C + URE2p strain.
The activity profile of the periplasmic asparaginase of Saccharomyces cerevisiae was determined during cell growth in an ure2 mutant; in an ure2 transformed with a plasmid containing the gene URE2 and, for comparison, in the strain D273-10B. Cells were cultivated in media presenting variable quantitative and qualitative nitrogen availability and the enzyme activity was evaluated in fresh and in nitrogen-starved cells. Nitrogen affected the asparaginase II level in fresh and starved cells of all strains. In the best condition, enzyme was produced by the wild-type cells at the late log-phase in the glucose/ammonium medium with a carbon to nitrogen ratio 4.3:1. Upon starvation, the activity doubled. The overall profile of the transformed strain was similar to that of the wild-type strain. In the ure2 mutant, high-enzyme levels were observed during growth, as expected. However the activity level, upon starvation, in proline grown cells, increased sixfold, suggesting that in addition to the Ure2p-Gln3p system, another system regulates asparaginase II biosynthesis.
Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Brazil.
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Oliveira
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Carvajal
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Bon
D001215:Asparaginase / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics*; D005838:Genotype; D005979:Glutathione Peroxidase; D009584:Nitrogen / Q000378:metabolism; D011328:Prions; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins
D005656:Fungal Proteins; D011328:Prions; D029701:Saccharomyces cerevisiae Proteins; D005979:Glutathione Peroxidase; C067020:URE2 protein, S cerevisiae; D001215:Asparaginase; D009584:Nitrogen