after setup crystallization screening, crystal were grown overnight in needle form. at this condition 5% Tacsimate 7.0 0.1M HEPES 7.0 10% PEG5K MME, but after 48 hours were disappeared, i have repeated using same protein but no crystal grown ? protein were purified using 50mM Tris 8.0 100mM Nacl 10mM glucose .
There may be several reason. One of them is temperature. Try growing at 4 degrees and if you get any hit, analyse at 4 donot take it to room temperature. Apart, from this any reaction which favours solubilisation of your protein may be affecting the crystals. Remember, crystallization is controlled precipitation. Try decreasing glucose and up PEG. Try gradient of both glucose and PEG.
there are many reasons some not mentioned is to do with protein concentration if the crystals are metastable the drop in protein concentration may cause them to redisolve and in that case they may not redisolve completely and maybe if you look closely at high mag you may see tiny micro crystals, Try starting with higher protein concentrations or adding extra protein when crystals are growing. Sometimes there is a degradation of protein during growth which is like a dramatic concentration drop run a gel on the drop to see if you have fragments.
Also consider the drop volume the dynamic of crystal growth can be different. Drops less than 200ul can grow faster but protein maybe depleted quickly larger drops may reach optimum conc slowly or not reach it at all and degradation may have time to take place
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