physical properties of protein - (May/05/2008 )

Hi:

I need to know how can I determine the physical properties of complement factor B experimentally after predicting them using ProParam tool in EXPASY website?

how is the half-life (T1/2) is practically determined?
how is the instability index ...................................?

Can any one find a reference for me because I was not able to find>>>>

http://www.ncbi.nlm.nih.gov/sites/entrez