I have grown some crystals after micro-seeding starting from thin-small
needles from needle-clusters. These crystals are larger in size than the
needles but are comparable to the shape and don't look like salt crystals.
But I cannot see the bands( its a complex) in the SDS-PAGE.I do not have a
home source,handy and would like to send these to the synchrotron.
Is it possible to NOT see a band of protein crystals in SDS-PAGE, if, say,
the amount of protein is < 1uG?
Protein to protein variation aside (which is usually within 2X),
conventional Coomassie R-250 staining gives very-easy-no-doubt detection
down to ~0.1 ug. 50 ng is still visible (assuming that the gel is any
good). Colloidal Coomassie G-250 ("Bradford") with destaining extends the
range down to 30-20 ng or 10 ng with some effort and special staining
solution. Proper silver staining should easily see 1 ng. I.e., a single
crystal that is a 50 um cube with 50% solvent puts you in the borderline
zone of "easy". Load many of them to be sure or use silver.
- Dima
