The JBS Floppy-Choppy is the rescue kit for proteins which are recalcitrant to crystallization. It enables the researcher to modify the protein target by in situ proteolysis to improve its crystallization behavior.
The method implies the addition of trace amounts of protease to the protein solution immediately prior to crystallization. Thus, the crystallization experiment is very straightforward. It can be set up without evaluating the efficacy of proteolysis, without stopping the proteolysis reaction and without purification of any proteolyzed protein fragments
In situ proteolysis is one of the most efficacious crystallization rescue strategies used at structural genomic centers [1,2]. Dong et al. (2007) In situ proteolysis for protein crystallization and structure determination.Nature Methods 4:1019.  Wernimont et al. (2009) In situ Proteolysis to Generate Crystals for Structure Determination: An Update. PLoS ONE 4: e5094