A simple method for growing protein crystals in the metastable
zone using the vapor diffusion technique is described.
The coverslips holding the hanging drops are transferred,
after being incubated for some time at conditions normally
giving many small crystals, over reservoirs at concentrations
that normally yield clear drops. Fewer, much larger and
better diffracting crystals are obtained, compared with
conventional crystallization at similar conditions. To
our knowledge, this is the first report of a significant
crystal improvement due to “backing off” from
nucleation conditions, using the hanging drop method.
A correlation of the transfer time with published results
for vapor diffusion equilibration of poly(ethylene glycol)
solutions is also presented.
