Fig. 2. HPLC purification of the S2-like immunoreactive peak 3 from Echinus esculentus. Seven HPLC steps were required to purify this peak and the final chromatogram is shown here. The S2-like immunoreactivity elutes in four fractions corresponding to a single peak of absorbance at 210 nm and amino acid sequencing of these fractions yielded the partial sequence MRYH.