Free Mounting^® System

The Proteros Free Mounting System (FMS) is a humidity control tool designed to enable macromolecular crystallographers to optimize individual crystals with respect to their diffraction characteristics. This new approach—to handle and improve protein crystal quality by directed control of humidity—offers substantial benefits for both the synchrotron and home lab environment, including: resolution, mosaicity, and anisotropy optimization, improved cryo-protocols, as well as reduced X-ray background.

The Free Mounting System allows accurate control of protein crystal water content, enhancing diffraction behavior of difficult crystals. Suitable for both beamlines and home lab applications, benefits include:

• Optimized resolution
• Optimized mosaicity
• Optimized anisotropy
• Improved cryo-protocols
• Reduced X-ray background

See the FMS in action:

• Change in diffraction as a function of humidity (AVI, 48 MB)
• Change in crystal volume as a function of humidity (WMV, 8 MB)

The FMS can lead to dramatically improved diffraction patterns and structural data as shown below:

Description and applications of the FMS

• Kiefersauer, R., Than, M. E., Dobbek, H., Gremer, L., Melero, M., Strobl, S., Dias, J. M., Soulimane, T., & Huber, R. (2000). A novel free-mounting system for protein crystals: transformation and improvement of diffraction power by accurately controlled humidity changes. J. Appl. Cryst. 33, 1223-1230.

• Estebanez-Perpina, E., Fuentes-Prior, P., Belorgey, D., Braun, M., Kiefersauer, R., Maskos, K., Huber, R., Rubin, H. & Bode, W. (2000). Crystal structure of the caspase activator human granzyme B, a proteinase highly specific for an Asp-P1 residue. Biol. Chem. 381, 1203-1214.

• Soulimane, T., Kiefersauer, R. & Than, M. E. (2001). Ba₃- Cytochrome c oxidase from Thermus thermophilus: purification, crystalllization and crystal transformation. Contribution for Elsevier Science/academic Press “Membrane Protein Purification and Crystallization: A Practical Guide, Second Edition”. ISBN: 0-12-361776-6

• Henrich, S., Cameron, A., Bourenkov, G. P., Kiefersauer, R., Huber, R., Lindberg, I., Bode, W. & Than, M. E. (2003) The crystal structure of the proprotein processing proteinase furin explains its stringent specifity. Nat Struct Biol, 10, 520-526

• Dobbek, H., Gremer, L., Kiefersauer, R., Huber, R. & Meyer, O. (2002). Catalysis at a dinuclear [CuSMo(=O)OH] cluster in a CO dehydrogenase resolved at 1.1-Å resolution. Proc. Natl. Acad. Sci. USA 99, 15971-15976

• Engel, M., Hoffmann, T., Wagner, L., Wermann, M., Heiser, U., Kiefersauer, R., Huber, R., Bode, W., Demuth, H. & Brandstetter, H. (2003) The crystal structure of dipeptidyl peptidase IV (CD26) reveals its functional regulation and enzymatic mechanism. Proc Natl Acad Sci USA, 100(9), 5063-5068

• Kyrieleis, O., Goettig, P., Kiefersauer, R., Huber, R. & Brandstetter, H. (2005) Crystal structures of the tricorn interacting factor F3 from Thermoplasma acidophilum, a zinc aminopeptidase in three different conformations. J Mol Biol. (2005) 349(4), 787-800

• Koch, M., Breithaupt, C., Kiefersauer, R., Freigang, J., Huber, R. & Messerschmidt, A. (2004) Crystal structure of protoporphyrinogen IX oxidase: a key enzyme in haem and chlorophyll biosynthesis EMBO Journal (2004) 23, 1720-1728

• Bowler, M, Montgomery, M., Leslie, A. and Walker, J. (2006) Reproducible improvements in order and diffraction limit of crystals of bovine mitochondrial F₁-ATPase by controlled dehydration, Acta Cryst. D62, 991-995