Protein StructureProtein Expression The success of the expression of (recombinant) proteins for protein structure analysis depends on many factors, one of which is the consistent and controlled growth of the cell line used. Digilab HiGro® offers high-capacity incubation and shaking for accelerated sample growth in microwell plates. This uniquely engineered instrument combines a small shaking orbital, gas flow and temperature control system in a user-friendly, compact layout. Plate-holding cassettes allow for easy loading and unloading. Protein Crystallization The protein crystallization process involves long wait periods of weeks or months during which the actual protein crystals are formed under controlled conditions. It is highly desirable to test more than one condition at a time to get results faster and to use only small amounts of proteins. Robotic nanoliter dispensing instrumentation can be used to rapidly set up large numbers of protein crystallization conditions. Digilab Honeybee is a bench-top system for the miniaturization of vapor diffusion and micro-batch protein crystallization experiments. Fast, precise and accurate non-contact dispensing of nanoliter volumes is achieved using proprietary Digilab technology: synQUAD™ dispensers couple high-speed micro-solenoid valves with high resolution syringe pumps for accurate and precise on-the-fly dispensing of volumes down to 50 nL. High accuracy on the x-y axis ensures correct positioning of the protein drop on top of the precipitant. In addition to vapor diffusion techniques (sitting drop and hanging drop), synQUAD™ technology enables micro-batch studies since the synQUAD™ channels have enough inertia to dispense through the oil layer. Counter Diffusion Counter diffusion offers several advantages over other crystallization methods. As the protein and precipitant solutions diffuse against each other within the capillary, a continuum of potential crystallization conditions is created resulting in the equivalent of several vapor diffusion experiments within each capillary. Additionally, crystals are often larger and of improved quality resulting in enhanced X-ray diffraction data. By scanning down the length of each capillary, the quality of the crystals can be evaluated while maintaining their environmental integrity (eliminating the need for manual crystal manipulation). Additives such as ligands or heavy atom derivatives can also be slowly diffused into the protein crystallization process for further biochemical and crystallographic requirements.
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