We are studying a human protein that we suspect has a tendency to aggregate in
vivo. After size exclusion chromatography and Western blot analysis of the
fractions with polyclonal antibodies,there are two strong signals: one in the
first fraction, and one in later fraction. Presumably the first fraction
contains an aggregated form of the protein. My question is: how do we show
that the protein present in both fractions is the same? We do not want to rely
on the antibodies only, and we cannot do microsequencing, the amounts are too
low. Limited proteolysis is not agood idea either if it is the same protein in
different conformations. Any suggestions, please?