help with protein elution - (May/11/2011 )

Hi,
I need some help with eluting heparin binding proteins from a scaffold. pH change may be the way.
Has anyone done it or have a protocol? proteins PI's are 7.5-10...
An important point - my scaffolds is crosslinked with calcium, and I don't want it to brake with elution, so may be calcium-contained buffer will be good...

Thank you!

Another important point - my scaffold is sulfated, (hence the interaction between the scaffold and the heparin binding proteins is electrostatic, with proteins being positively charged)...

Thank you!