Hello all I am working on small protein-protein complex of 10 kDa each component.Among these complex one of the partner known to be highly
flexible but in complex they are suppose to be well structured and from a tight complex . I am trying to crystallise this complex. When i add the protein in crystallisation solution it precipitates immediately in the crystallisation drop and make slightly yellowish precipitate in most of the consitions (90%). Conditions in which this proteins either doesnot precipitate or precipitate with slight delay are either have PEG or Tris-cl Ph=8.5 buffer. Even the condition which have amm. sulphate like precipitants and Tris pH=8.5 as a buffer, it precipitates immediately. I am using protein concentration of 15 mg per ml in buffer Tris-cl Ph=8.0, 100mM NaCl and 1% Glycerol. This protein forms a slimy yellow deposition on the membrane surface of the centricon while concentration of the protein.Can any one suggest what could be the problem under this scenario? suggestions to avoid the precipitaion of the protein under crystallisation condition as well as to avoid the slimy deposition fromation on the bed of membrane of the centricon. I will highly appreciate the comments. I would also like to know even the comments about the crystallisation trouble associated with the unstructured or flexible proteins. Thanks in advance Regards peter
