A LONG WAY TO WELL DIFFRACTING PROTEIN CRYSTALS

Ľubica Urbániková

Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 84551 Bratislava 45, Slovak Republic

In experiments of protein crystallization very often spherulites, microcrystals and needles appear as a result of not having optimal crystallization conditions. Optimization of conditions is often guided by a sense of protein, however, theoretical knowledge and practical experiences are inevitable. It is well known that the best conditions for growing crystals differ from crystal nucleation conditions. Separation of these two processes in order to obtain well diffracting crystals will be presented. The importance of protein purity and homogeneity in growing crystals will be stressed and procedures improving crystal quality will be discussed. One of the topics will concern practical aspects for preparation of protein crystals for data collection at room and cryogenic temperature. All these points will be documented by our experiences with crystallization of a number of proteins, their mutants and complexes.