Mass spectrometric analysis of the electroeluates of fluorescent proteins after preparative electrophoresis in the automated HPGE-1000 apparatus

Bands of green fluorescent protein (GFP) and R-phycoerythrin (PHYCO) in gel electrophoresis on the automated apparatus for gel electrophoresis with pe riodic fluorescence scanning (HPGE), the HPGE-1000 apparatus, were retrieve d from the gel by electroelution. While PHYCO was recovered in a single vol ume of electroeluate buffer after the predicted migration time, GFP fluores cence was lost under the same conditions and could only be recovered using multiple changes or electroeluate buffer. The multiple volumes of buffer ne cessitated pooling, concentration, and storage, conditions under which a mi nor GFP component, GFP-II, formed artifactually. PHYCO after electroelution also exhibits a minor component present in the original preparation. The e lectroeluate of GFP, transferred into a mass spectrometer after pooling, co ncentration and storage, is indistinguishable in mass from the original pre paration.