SUMMARY: In , the amount of glutamine synthetase is finely attuned to the availability of ammonia in the culture medium, and any change in ammonia availability results in a compensatory adjustment to enzyme level. In yeast growing with different sources of nitrogen there was a good inverse correlation between the rate of enzyme synthesis and the size of the cell pool of glutamine: glutamine and not ammonia appeared to act as a co-repressor of the formation of glutamine synthetase.

Sudden changes in ammonia availability or carbon supply could lead to the inactivation of glutamine synthetase. This was shown to be associated, under some conditions, with a marked increase in the pool of glutamine and it is possible that it was brought about by sudden changes in the relative cell concentrations of glutamine and glutamate. However, the process is clearly more complex than this and catabolism of carbon substrates is also involved.

The specific activity of the NAD-specific (deaminating) glutamate dehydrogenase also varied with the availability of ammonia, but neither it nor glutamine synthetase was subject to parallel regulation.


Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error