Abstract: The reversible phosphorylation of proteins is important in intercellular communication. The most frequentlyphosphorylated amino acid in proteins is phosphoserine (P-Ser);however, phosphothreonine(P-thr),phosphotyrosine (P-Tyr).And phosphoarginine(P-Arg) are also found in decreasing frequency. The derection of phosphorylated amino acids in thepresence of amino acids is important to an understanding of the role of many proteins, some of which are involved in signaltransduction pathways.We have shown that separation of these phosphoamino acids in the presence of similarly charged amino acids,such as asparticacid(Asp) and glutamic acid (Glu) can be effectively done by capillary electrophoresis (CE) with indirect detection usingadenosine monophosphate(AMP). Baseline resolution of P-Tyr,P-Ser, without interference of Asp and Glu or residual phosphate,in about 18 min with detection limits of 1 mg/L(3～6μm) for the phosphoamino acids is possible.This CE method has been usedto follow the acids hydrolysis of phosvitin,a P-Ser containing protein, and the number of residues found correlates statisticallyto the molybdate colorimetric method.

Key words: sepraration, determination, phosvitin, capillary electrophoresis, photometric detection