One example of such an analysis is Figure 3. Certain crystallization screen conditions result in the formation of a massive shower of rod-like crystals from a recombinant chaperone protein (Jochen Reinstein Group / Ilme Schlichting Group, Dep. Biomolecular Mechanisms). Individual crystals can be teased out and washed (Figure 3B). After transfer to the Maldi plate, the crystal is dissolved and analyzed (Figure 3C). Anylyses of the starting protein solution, the wash solutions and the dissolved crystal show that, in this case, the protein molecules in the crystal have m/z values identical to that of the starting material. In those quite common situations where this is not the case, PMF mass spectrometry has proven indispensable in identifying the missing amino acids, which can be invaluable for (re)interpretation of electron density maps and/or for new cloning/protein experiments. Maldi TOF analysis of a single protein crystal. A crystallization reaction of a recombinant molecular chaperone protein prduces a shower of crystals (A), from which a single crystal was isolated (B) and subsequently washed. Maldi TOF analysis demonstrated that the protein in the crystal was identical to that in the starting solution.