conjugation of phosphatidyl serine to protein - conjugation techniques to insure solubility (Apr/18/2008 )

Hello,
Can anyone share with me protocol or idea for conjugation of phosphatidylserine to BSA? I have solubilized the the PS in THF and BSA in MES buffer. Carbodiamide is the cross-linker. The reaction mixture is clear but removal of the THF (by dialysis) causes precipitation of the protein. Suggestions??

try DMSO for PS and PBS for protein