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Sample Preparation

For academical use for members of the Heinrich-Heine-University and external users we provide a widespread scientific support and service.

For crystallization the proteins have to fulfill some minimum prerequisites, that will be explained in detail below.

We provide a widespread screening for crystallization conditions by means of the „sitting drop“ method, for soluble proteins as well as for membrane proteins. We are able to check about 2500 different conditions in an initial screening. Our service contains consultation, implementation, documentation and evaluation of the experiments over a 4 weeks period. Apart from screens with the apo-protein we can also set up co-crystallization trials with your protein plus substrate(s). For the screening we invoice incurred material expenses only (e. g. crystallization plates, sealing foil, screening kits, fine chemicals).

To ensure an optimal screening and a good reproducibility some aspects are of importance and some documents/chemical agents are needed (see also order from):

  1. the low molar protein buffer should contain as less agents as possible (just as much as is required for protein stability; if possible avoid phosphate buffer)
  2. protein needs to be pure (at least 90 % on SDS-PAGE), and homogenous (only one oligomeric state)
  3. protein has to be stable over at least three weeks (at 4 °C, 12 °C or 20 °C)
  4. protein concentration at least: 5 - 10 mg/ml
  5. minimum protein volume per screen (96 conditions): 15 µl
  6. please provide about 2 ml protein buffer with declaration of all ingredients

Furthermore some information are essential for our experiments:

  1. date of the protein purification and storage/stability conditions
  2. image of SDS-PAGE and homogeneity verification (e. g. gel filtration)
  3. protein concentration, molecular weight and composition of the protein buffer
  4. if the protein requires certain ligands (like metal ions, cofactors etc.) for activity and/or stability, please state
  5. is there an activity assay? If so: please ensure that the protein is still active in the used buffer.
  6. In case of co-crystallization trials: please state the substrate(s) and suitable concentration(s). Include the substrate(s) in the delivery unless they are commercially available.

On request we offer further experiments, starting from optimization of the initial crystallization condition, searching for cryo-conditions for diffraction measurements and crystal characterization at the in house X-ray source up to data collection at a synchrotron and subsequent structure determination.

For further information or appointments please contact us.

For conduction of the experiments we additionally need some further information about the protein and possibly agents, wherfore we need a filled in order form and therein mentioned documents for every project.

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