Subject: [Protein-analysis] Re: heterooligomer or homooligomer
I would have a suggestion how to solve the
heterooligomer/homooligomer problem in case that the sample fulfills the
1. the protein complex originates from an
organism with a fully sequenced genome.
2. the 200 kDa-gel filtration fraction
already is reasonably pure.
3. the sequence has cleavage sites for trypsin
(what many proteins in this MW-range will have)
In this case you could cut out the major
bands either from 1D-SDS-PAGE or the major spots from a 2D-gel of this
purified 200kDa-gel filtration fraction, digest the bands/spots using a
suitable protease (trypsin?) and investigate all samples using MALDI-MS. In case
of a homooligomer you should identify the same protein as the dominant
protein in all samples. If you, however, find a different protein as the main
constituent of one of these dominating spots you will have reason to believe
that this is a heterodimer.