buh bye GST!

[Rachel Blair]

hello there,
i need to remove the GST fusion partner from a protein expressed from
the pGEX 3x vector (Pharmacia).  there is a factor Xa cleavage site
engineered between the GST and my protein of interest.  does anyone know
the best source for factor Xa in small quantites AND have an
accompanying protocol for its use?  (Sigma, for example, sells it in 10
U quantities but has no guidelines for its use in this application. 
Pharmacia, on the other hand, only sells it in 400 U quanitites +
protocol for $300!)  please e-mail me directly if you can help.

much thanks,
rachel