You CAN, but the zinc fitting might galvanically corrode in conjunction with copper pipes... Perhaps not a wise choice, although without knowing the potential of Zinc I couldn't say for sure.
Ok Edit, Zinc has a similar potential to aluminum and anyone who'se ever tied to have aluminum and copper connected via water knows much corrosion goes on there :eek2:
So to sum up, you can use it for a little while, but don't expet it to last longterm say 3-6 months before serious corrosion sets in.