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KMID : 0364819880260030215
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Korean Journal of Microbiology
1988 Volume.26 No. 3 p.215 ~ p.222
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Effect of Methionine Sulfoximine in nitrogenase activity by ammonia and glutamine in Rhodopseudomonas sphaeroides
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Lee Hye-Joo
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Abstract
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1
The effect of ammonia and glutamine on nitrogenase activity of Rhodopseudomonas sphaeroides was examined. The nitrogenase activity of this strain was inhibited by ammonia and glatamine. When ammonia and giatamine were exhausted, nitrogenase activity promptly resumed at its original rate.
Methionine sulfoximine (MSX), irreversible giutamiue synthetase (GS) Inhibitor, is a structural analogue of glutamate. MSX was used in order to know whether the uhrogenase activity was inhibited by ammonia and glutamine directly or not. The ability of MSX to prevent ultrogense switch-off by ammonia was found to be dependent upon the phase of culture. When the cells were sampled after 12 boar culture, 500μM MSX would not prevent the nitrogenase switch-off by ammonia. Twenty one percents of GS activity was inhibited by 500μM of MSX and concentration of reigned ammonia decreased. Bet nitrogenase activity was still inhibited by ammonia. However, nitrogense switch-off after 20 hours would be prevented by 100pM of MSX. On the other band, GS activity was inhibited completely by 100 pM MSX and concentration of released ammonia somewhat increased. But nitrogen a activity was not inhibited. This data Indicated that the inhibition of in vivo nitrogenase activity of Rp. sphaeroides by ammonia seemed to be mediated by products of ammonia assimilation rather than by ammonia itself.
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