THE BUTTON TEST - A SMALL-SCALE METHOD USING MICRODIALYSIS CELLS FOR ASSESSING PROTEIN SOLUBILITY AT CONCENTRATIONS SUITABLE FOR NMR

A simple method has been developed for screening solution conditions t o determine conditions under which a protein is soluble at the high co ncentrations typically used for NMR spectroscopy. The method employs m icrodialysis cells or 'buttons'. The low sample volume (5 mu l) requir ed for each microdialysis button permits testing of a wide range of so lution conditions and temperatures with high protein concentrations, u sing a small amount of protein. Following precipitation of several NMR samples of the C-terminal core domain of human TFIIB, the microdialys is button screen facilitated identification of conditions in which pre cipitation of the TFIIB core domain was eliminated. The microdialysis button method for screening solution conditions is generally applicabl e and has been used to permit rapid identification of suitable NMR sam ple solution conditions for proteins involved in transcription and cel l adhesion.