So i seem to be very stuck with a question, and I was hoping some of you could give me a helping hand -- point me in the right direction

The question is:

Carbonic anhydrase of erythrocytes (Mr 30,000) has one of the highest turnover numbers we know of. It catalyses the reversible hydration of CO2.

If 10 ug of pure carbonic anhydrase catalyses the hydration of 0.30g of CO2 in 1 min at 37 degrees celcius at Vmax, what is the turnover number of carbonic anhydrase (in units of min-1)?

Now I know Vmax=kcat x [E] but I couldn't really get further from there as I had problems calculating [E] -- so any help would be greatly appreciated!

Thanks