it would not be active in water. Use 50mM Tris, pH8, 150mM NaCl, 5mM CaCl2, 2uM, and 0.01%Brij-35.

Enzyme reactions should always be performed in a pH buffered solution (the purpose of the Tris in Marcia Moss's answer) to keep the pH from changing during the reaction. The pH is usually selected to be optimal for the activity of the enzyme. Enzymes have pH optima for activity because they contain amino acid side chains that have ionizable side groups (lysine, glutamate, aspartate, cysteine, histidine, arginine, tyrosine) due to dissociable protons. The state of protonation of these side chains in the active site often plays a major role in catalysis.

Matrix metalloproteinases require Ca2+ ions for their activity, as wells Zn2+.

Thank you very much Dr. Marcia Moss for your kind information also Dr. Adam B Shapiro, thank you very much for delivering such a great knowledge for me.   

Could you please give me any reference article which explains the catalytic activity of MMP-2 and the above buffer dependence on its activity?

Here I am using activated MMP-2 from CalBochem

http://www.emdmillipore.com/US/en/product/MMP-2%2C-Active%2C-Human%2C-Recombinant%2C-CHO-Cells,EMD_BIO-PF023

In this case as Dr. Marcia Moss said  50mM Tris, pH8, 150mM NaCl, 5mM CaCl2, 2uM, and 0.01%Brij-35. will work?  In this case do I need to use Zn2+ component in the buffer ?  Also HEPES or Tris which one will be better?

Dr. Adam B Shapiro, could you please give me few reference article which describes the catalytic activity of MMP-2, as you told MMP need Ca2+ ions for their activity, as wells Zn2+?

zinc is not required. Hepea would probably work. Never heard of anyone using it.

I know from running assays myself, calcium is needed in the buffer. Zinc is not.

reference for Mmp2http://www.uniprot.org/uniprot/P08253

Thank you very much Dr. Marcia Moss for the kind information.  I have read your few articles will be helpful for my future research.

you are welcome

Use tris Hcl buffer (50mM) of pH 7.6 along with CaCl2, ZnCl2 and Nacl

Did this activated MMP-2 work well? Where did you buy it? And what the enzymatic buffer were used at last?

HEPES does work and it won't block your N-termini if someone would want to do Edman sequencing

Is Brij-35 totally necessary? I don't have it in our lab unfortunately. Would another surfactant work? Like triton X-100?