Hello,
I am purifying peptides from coelenterates using
chromatography methods. After each separation step
the fractions collected are tested for biological
activity in cells that express acetylcholine receptors (it is known that peptides are the responsible for this activity). After the first step, the activity was localized in only one fraction but when I increase
separation in the second chromatography the activity was localized in 5 fractions. I am sure
that any of these new fractions are pure so I should continue fractionating, but, which of them
should I select ?
What is the criterion to follow ?
I have been recommended to follow de criterion
activity/peptide amount. There are fractions
with low activity and very very small amount of peptide. Of course, the calculations favours these fractions with low amount of peptide. To purify these fractions is not practical for me since characterization will be very difficult because of the small amount of peptides. Furthermore I don't know how "noisy"
are the low values of activity.
Maybe to follow the criterion of the more active
fraction without considering the amount of peptide
will be better for characterization. What do you think about it ? Thank you.