In article <9FEB95.21261996 at skyfox.usask.ca> matte at skyfox.usask.ca writes:
> We have been growing protein crystals in
>hanging drops, at various temperatures (ie. 4, 10
>16, 21 C) from either salt or PEG solutions, but
>they are invariably hollow in nature. It seems that
>this is most likely due to the crystals growing too
>fast once nucleation has taken place. I have read
>that poisoning the mother liquor (with detergent,
>etc) can sometmes help. Does anyone have any other
>suggestions based on experience with this problem ?
About them growing too fast you are almost certainly
correct. I believe this happens because the mother liquor
becomes locally depleted at the center of a rapidly growing
face. In this case it looks like spontaneous nucleation
does not occur until the drop is very supersaturated-- you
might try microseeding a variety of starting conditions below
the pptant conc. where crystals are known to appear in order
to have a nucleus present at the outset of supersaturation.
Reducing the volume of the well solution or moving off of
ideal ph (along with seeding) may perhaps benefit.
W. E. Meador