Article Abstract:
The enzyme secreted by Treponema denticola, Treponema vincentii and Treponema socranskii, which hydrolyzes hyaluronic acid (HA) and chondroitin sulphate (CS), was visualized directly from culture supernatants. The affinity-purified extracellular enzyme of T. denticola has a single molecular species with a molecular mass of 59 kDa. The enzyme, called hyaluronoglucosaminidase, has been localized at the cell surface and may play an active part in the degradation of connective tissue ground substance in the initiation and progression of periodontal disease.
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Article Abstract:
Experiments were performed to isolate and characterize 10 complementation groups of Hansenula polymorpha mutants with reduced or undetectable nitrate reductase (NR) activities. Results showed that while NR activity is only induced in the presence of nitrate, the presence of ammonium or other reduced nitrogen sources inhibits this activity. These findings indicate that NR synthesis was dependent on the repression mechanisms produced by ammonium and the induction phenomena induced by nitrate.
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Article Abstract:
A study was conducted to analyze the cloning and preparation of the thiD/J gene of Escherichia coli supporting a thiamin-synthesizing bifunctional enzyme. The genes encode hydroxyethylthiazole kinase, hydroxymethylpyrimidine (HMP) kinase and phosphomethylpyrimidine kinase. The thiD product was determined from cell-free extracts. Results indicated that HMP kinase and HMP-P kinase are bifunctional enzyme encoded by the gene thiD/J.
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