asparagine synthetases

[Mohohlo.Molatudi]

I have been trying to create E. coli asparagine mutants using transposon 
mutagenesis. I know that there are two genes coding for asparagine 
synthetase A and B which I need to inactivate in order to achieve this. I 
think that it would help to know the pH optima of the two synthetases. Well, 
I know that synthetase A has optimum activity at pH 8.4 but have been unable 
to find anything in the literature about optimum pH for synthetase B. Can 
anyone help ?

Cheers.

Mohohlo Molatudi
Dept. Botany
University of Natal (Pietermaritzburg)
South Africa