Peptide was isolated from water extract of radix isatidis by using strong cation exchange chromatography column( SP- 5PW) and hydrophobic interaction chromatography( POROS HP2),their biochemical characters were investigated,subsequently. The peptide,which purified by using the method above,was identified to be homogeneous by Tricine- SDS- PAGE. Its relative molecular weight was estimated to be approximate 6. 87 ku. Its p I was estimated to be 7. 73 by isoelectric focusing electrophoresis. Its N- terminal se...