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pubmed:abstractText |
In the presence of DL-alanine intracellular cyclic AMP in nonproliferating cells of Brevibacterium liquefaciens increased rapidly to the maximum level of approximately 180 muM, and extracellular cyclic AMP increased to 100 muM within 4 hr at 25 degrees . Adenylate cyclase (EC 4.6.1.1) induction was not observed during this incubation. The concentration of pyruvate in the total culture increased concomitantly with that of cyclic AMP and reached approximately 20 mM after 4 hr of incubation. Since the activity of cyclic nucleotide phosphodiesterase is extremely low in this bacterium, the accumulation of cyclic AMP with DL-alanine appeared to be due to the activation of adenylate cyclase by pyruvate. D-alanine was more effective than L-alanine in producing pyruvate, and a high activity of D-alanine oxidation was detected in the cell lysate of B. liquefaciens.Thus, adenylate cyclase in this bacterium appeared to be regulated in vivo by pyruvate which was formed, in this case, predominantly from D-alanine through the action of D-aminoacid oxidase (EC 1.4.3.3). Pyruvate, added extracellularly, also caused a rapid accumulation of intracellular cyclic AMP. Glucose did not change the level of cyclic AMP significantly. It also did not affect the intracellular accumulation of cyclic AMP with DL-alanine.
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