[ccp4bb]: crystal screening

[jenny hu]

I'm trying to grow crystals for 1 mutation and tried the screen 1 and PEG/ION kit from HAMPTON.But most of them are still clear, does this mean, the concentration of the proteins are still too low?But it's already around 50mg/mL.Are there any other good screening kits available?The literature reported the wild type protein grow crystals at very acidic condition(pH=3.0), should I just use the condition around this?Another question is , for small needle crystals, is there any way that I can get bigger crystals?
Thanks a lot.