Characterization and enzymology
There are several protein characterization tools aimed at characterizing various properties of the protein sample at the Faculty of Biochemistry and Molecular Medicine such as:
Further protein characterization
Some useful characterization for the protein sample before the structural studies, such as CD spectroscopy or ITC, can be done in the Protein biophysical measurement and amino acid analysis facility.
It is assumed that the protein has been well purified and is pure on an overloaded SDS-PAGE analysis. As a rule of thumb, the protein samples obtained from his-tag affinity chromatography are not pure enough. It is best to have at least one ion exchange column in the purification protocol, in order to avoid charge heterogeneity of the protein sample. The last purification step is always a size-exclusion column. The best crystallization results are obtained when using only the central part of the peak fractions. Each characterization technique has different requirements for buffer, buffer concentration and protein concentration. Consultation with the local staff is required to discuss these issues, as they depend also on the properties of the protein to be investigated. Knowledge of the isoelectric point of the protein is important for setting up the ion exchange chromatography.