The Free Mounting System from Proteros biostructures and Rigaku provides a state-of-the-art humidity control for your sample. In single crystal X-ray structure determination, this could mean the difference between obtaining a structure or not. And getting the structure means publications and more funding. Consider what this could do to your productivity. How would you like to improve the diffraction of your current crystals without running additional crystallization trials? You might be able to with the Free Mounting™ System (FMS) by Proteros and Rigaku Americas Corporation. In only a few years the number of successful uses of the FMS is increasing, including both soluble and membrane-bound proteins. In addition to searching for improvements in protein diffraction, the FMS has proven an easy tool for testing room temperature diffraction. Using the FMS is relatively easy. You need solutions, crystals, loops, pins, and of course water...all available in the typical structural biology laboratory. Additionally, you need an X-ray system for recording the diffraction images. When determining the start relative humidity, one takes a drop of the mother liquor and places it in a fully contained loop. The silhouette of the drop is monitored for changes in area. The FMS is started at some arbitrary relative humidity (RH). If the RH in the FMS (RHfms) is higher than the RH of the solution (RHdrop), then the drop will absorb humidity and grow making the area increase. The RH of the FMS must be lowered. If RHfms is lower than RHdrop, then the drop will lose humidity and the area will decrease. Here the RH of the FMS must be raised. When RHfms equals RHdrop, then the system is at equilibrium and this is the RH of your crystal. Schematic drawing: crystal (mounted in a standard loop) sits on an inner axis, that can be rotated independently from casing. Whole head is temperature controled (T-sensor close to the opening) to maintain a stable humidity. Humid air adopts correct temperature (and therefore humidity) in the head before entering the central chamber, where the crystal is located. The crystal protrudes from the outlet by a few millimeters to allow for X-ray exposure. The image on left hand side shows the FMS head in its open state with a loop mounted. The image on right hand side illustrates the FMS head mounted on a diffractometer. There are numerous ways to approach an experiment with the FMS. Usually, dehydration is attempted first with rehydration afterward. Here is shown an experiment where old crystals in dehydrated wells were trying to be recovered. The FMS was set to a relatively low RH determined from the drop solution (this is where it was identified as drying out), the RH raised and then lowered. The scheduled RH from the FMS is the solid line; the actual RH in the FMS stream is shown as a hashed line; and the actual RH of the crystal is represented as a dotted line. Note that the RH of the stream lags behind the schedules RH, and the RH in the crystal lags behind the RH of the stream. The latter lag time is dependent on several things including size of crystal, nature of water and precipitants in channels of crystal, temperature, and the RH itself. Once studies have determined not only the ideal RH but also the method of approaching that ideal RH, a crystal can be set to this condition. The crystal is then coated with oil (PerFluroPolyEther, or PFPE), any excess oil wicked away, the crystal/loop/pin is removed from the FMS head, and the crystal is flash-cooled. This crystal is now available for low temperature data collection. Please feel free to contact some of these authors about their successes. Or contact us with your questions by e-mail or phone: 281-362-2300.");
The Free Mounting System from Proteros biostructures and Rigaku provides a state-of-the-art humidity control for your sample. In single crystal X-ray structure determination, this could mean the difference between obtaining a structure or not. And getting the structure means publications and more funding. Consider what this could do to your productivity.
How would you like to improve the diffraction of your current crystals without running additional crystallization trials? You might be able to with the Free Mounting™ System (FMS) by Proteros and Rigaku Americas Corporation.
In only a few years the number of successful uses of the FMS is increasing, including both soluble and membrane-bound proteins. In addition to searching for improvements in protein diffraction, the FMS has proven an easy tool for testing room temperature diffraction.
Using the FMS is relatively easy. You need solutions, crystals, loops, pins, and of course water...all available in the typical structural biology laboratory. Additionally, you need an X-ray system for recording the diffraction images.
When determining the start relative humidity, one takes a drop of the mother liquor and places it in a fully contained loop. The silhouette of the drop is monitored for changes in area. The FMS is started at some arbitrary relative humidity (RH). If the RH in the FMS (RHfms) is higher than the RH of the solution (RHdrop), then the drop will absorb humidity and grow making the area increase. The RH of the FMS must be lowered. If RHfms is lower than RHdrop, then the drop will lose humidity and the area will decrease. Here the RH of the FMS must be raised. When RHfms equals RHdrop, then the system is at equilibrium and this is the RH of your crystal.
Schematic drawing: crystal (mounted in a standard loop) sits on an inner axis, that can be rotated independently from casing. Whole head is temperature controled (T-sensor close to the opening) to maintain a stable humidity. Humid air adopts correct temperature (and therefore humidity) in the head before entering the central chamber, where the crystal is located. The crystal protrudes from the outlet by a few millimeters to allow for X-ray exposure. The image on left hand side shows the FMS head in its open state with a loop mounted. The image on right hand side illustrates the FMS head mounted on a diffractometer.
There are numerous ways to approach an experiment with the FMS. Usually, dehydration is attempted first with rehydration afterward. Here is shown an experiment where old crystals in dehydrated wells were trying to be recovered. The FMS was set to a relatively low RH determined from the drop solution (this is where it was identified as drying out), the RH raised and then lowered. The scheduled RH from the FMS is the solid line; the actual RH in the FMS stream is shown as a hashed line; and the actual RH of the crystal is represented as a dotted line. Note that the RH of the stream lags behind the schedules RH, and the RH in the crystal lags behind the RH of the stream. The latter lag time is dependent on several things including size of crystal, nature of water and precipitants in channels of crystal, temperature, and the RH itself.
Once studies have determined not only the ideal RH but also the method of approaching that ideal RH, a crystal can be set to this condition. The crystal is then coated with oil (PerFluroPolyEther, or PFPE), any excess oil wicked away, the crystal/loop/pin is removed from the FMS head, and the crystal is flash-cooled. This crystal is now available for low temperature data collection.
Please feel free to contact some of these authors about their successes. Or contact us with your questions by e-mail or phone: 281-362-2300.");
