Utilisation of adsorption and desorption for simultaneously improving protein crystallisation success rate and crystal quality.

High-quality protein crystals of suitable size are an important prerequisite for applying X-ray crystallography to determine the 3-dimensional structure of proteins. However, it is often difficult to obtain protein crystals of appropriate size and quality because nucleation and growth processes can be unsuccessful. Here, we show that by adsorbing proteins onto porous polystyrene-divinylbenzene microspheres (SDB) floating on the surface of the crystallisation solution, a localised high supersaturation region at the surface of the microspheres and a low supersaturation region below the microspheres can coexist in a single solution.

Glycan analysis of Prostate Specific Antigen (PSA) directly from the intact glycoprotein by HR-ESI/TOF-MS.

Glycans are important modulators of the biological function of proteins and are normally characterized from proteolytic glycopeptides or from (N-)glycans released enzymatically by glycosidase treatment or chemically by hydrazinolysis. We demonstrate that glycan compositions can easily be determined directly by LC-ESI/TOF-MS from intact glycoproteins even with a very complex glycosylation pattern. Interpretation of isotopically resolved mass spectra of prostate specific antigen (PSA) using bioinformatics tools gives within a few hours the glycan compositions of 38 glycoforms.

Interlaboratory study on differential analysis of protein glycosylation by mass spectrometry: the ABRF glycoprotein research multi-institutional study 2012.

One of the principal goals of glycoprotein research is to correlate glycan structure and function. Such correlation is necessary in order for one to understand the mechanisms whereby glycoprotein structure elaborates the functions of myriad proteins. The accurate comparison of glycoforms and quantification of glycosites are essential steps in this direction.