Development, validation and application of a liquid chromatography-tandem mass spectrometry method for the activity and inhibition of DPP-4.

Inhibition of the enzyme dipeptidyl peptidase 4 (DPP-4) is a pharmaceutical treatment for type 2 diabetes. To demonstrate bioequivalence of enzyme inhibition of a new dosage form of the inhibitor vildagliptin, a method for enzyme activity was developed, validated and applied using liquid chromatography and tandem mass spectrometry (LC-MS/MS). The method was validated fit for purpose, including accuracy, precision as well as the stability of the activity and the inhibition of DPP-4 in human plasma.

Isolation of plant cell wall proteins.

The quality of a proteomic analysis of a cell compartment strongly depends on the reliability of the isolation procedure for the cell compartment of interest. Plant cell walls possess specific drawbacks: (1) the lack of a surrounding membrane may result in the loss of cell wall proteins (CWP) during the isolation procedure; (2) polysaccharide networks of cellulose, hemicelluloses, and pectins form potential traps for contaminants such as intracellular proteins; (3) the presence of proteins interacting in many different ways with the polysaccharide matrix require different procedures to elute them from the cell wall. Three categories of CWP are distinguished: labile proteins that have little or no interactions with cell wall components, weakly bound proteins extractable with salts, and strongly bound proteins.

Optimization and evaluation of surface-enhanced laser-desorption/ionization time-of-flight mass spectrometry for protein profiling of cerebrospinal fluid.

Cerebrospinal fluid (CSF) potentially carries an archive of peptides and small proteins relevant to pathological processes in the central nervous system (CNS) and surrounding brain tissue. Proteomics is especially well suited for the discovery of biomarkers of diagnostic potential in CSF for early diagnosis and discrimination of several neurodegenerative diseases. ProteinChip surface-enhanced laser-desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) is one such approach which offers a unique platform for high throughput profiling of peptides and small proteins in CSF.

Proteomic analysis of secreted proteins from Arabidopsis thaliana seedlings: improved recovery following removal of phenolic compounds.

Arabidopsis thaliana seedlings grown in liquid culture were used to recover proteins secreted from the whole plant. The aim was to identify apoplastic proteins that may be lost during classical extraction procedures such as preparation of cell walls. The inclusion of polyvinyl-polypyrrolidone (PVPP) in the protocol of purification of secreted proteins allowed a more efficient identification of proteins after their separation by two-dimensional gel electrophoresis (2-DE) and mass spectrometry analyses.

Structure-efficiency relationships of zwitterionic detergents as protein solubilizers in two-dimensional electrophoresis.

Several zwitterionic detergents differing in their polar heads, linker parts and hydrophobia tail were synthesized and evaluated for their efficiency in protein solubilizers for two-dimensional electrophoresis. A model system consisting of human red blood cell ghosts was used for this purpose. This study leads to the description of several new efficient detergents and allowed us to derive structural constraints for the design and synthesis of efficient detergents for two-dimensional electrophoresis.