A simple method of eluting proteins from two-dimensional gels.

Apo A-I lipoprotein was extracted from the appropriate pieces of two-dimensional gel patterns, by electrophoresis onto hydroxylapatite overlaying a slab of polyacrylamide sodium dodecyl sulfate gel. The extracted protein was then eluted from the hydroxylapatite by washing with increasing concentrations of phosphate buffer. The recovered protein was electrophoretically homogeneous. We believe that this method can be generally useful in the purification, for study, of proteins identified on two-dimensional gels as putative markers of disease.