I did protein extraction from fruit (Curculigo latifolia) according to the
attached protocol. I got the white pellet. but while i left it to air dry
briefly, i saw the color of pellet got darker, in some parts, it changed to
black. i think while i took the phenol phase, unwanted substances entered.Do
you have any idea of the type of the substance that causes this,
then the pellet was solubilised with urea, thiourea, chaps. agitated for
two hours at 4 degree then no parts of pellet remained and all solubilised.
then i centrifuge at 12000g for 10 min, in one tube a white substance and in
another one an almost dark substance precipitated. i took the supernatant
for bradford protein assay.
i would be grateful if you could help me identify these unwanted substances.