An electrophoretic technique that is especially interesting for the study of proteins is called

"isoelectric focusing." In this method electrophoresis is carried out across a medium that

supports a pH gradient. The pH gradient and cell polarity are such that the cathode end of the

column is relatively basic. Thus a positively charged protein gradually loses its charge as it

migrates, finally coming to rest at a pH corresponding to its isoelectric point. Carlstrom and

Vesterbergt used this method to study the heterogeneity of peroxidase from cow's milk. After

focusing was achieved, the column was drained and the $pH$ and absorbance $($at $280nm)$ of

successive fractions of eluent were measured:

How many components does this sample apparently contain? What are the values of the

isoelectric points for each?