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The quantification of proteins in a complex biological sample is an important and challenging task. Mass spectrometry (MS) is increasingly used for this purpose, not only to give a global [...]

The use of a mass spectrometer in quantitative analysis exploits its exquisite selectivity and sensitivity as a detector, allowing a signal to be ascribed to a particular chemical entity with [...]

A research shows that compounds like disulfide S-monoxide (DSMO) and disulfide S-dioxide (DSDO) act as proximal mediators for the modification of various proteins, which is mediated by several oxidants. The analysis of the model of the protein kinase C (PKC) shows that the disulfide S-oxides (DSOs) from different thiols and oxidative states have completely different effects on the protein and can even cause distinct cellular responses on being derived from several cellular reactions.

The report stated that electrospray ionization high-pressure mass spectrometry was used to determine the enthalpy, entropy and gibbs free energy for the equilibrium gas-phase ion-molecule association reactions of C(sub m)H(sub 2m+1)NH(sub 3)(super +)(m = 1-8),CH(sub 3)(sub 3)NH(super +) with one to there water ligands. The results show that the addition of water ligand to the monohydrated alkylammonium ion results in an increased stabilization in its structure and binding.

The identification of binding partners of proteins by mass spectrometry following specific capture on a biosensor surface is a promising tool for proteomics research and the identification and characterization of protein-protein interactions. Previous approaches include the direct ionization of analyte from the biosensor chip on a matrix assisted laser desorption ionization time-of-flight mass spectrometer (MALDI-TOFMS) apparatus and the on-chip digestion followed by elution, chromatographic concentration of the fragments, and electrospray mass spectrometry. In the present paper, using the small-volume microfluidic sample manipulation technique with oscillatory flow reported recently (Abrantes et al. Anal Chem. 2001, 73, 2828-2835), analyte is shown to be eluted from the sensor surface into a small volume of buffer that promotes dissociation from the capture surface and delivery to the mass spectrometer. Both the incubation of the sensor surface with the sample and the recovery of analyte can be achieved with a few microliters and conducted until steady-state is attained. Because the procedure is nondestructive for the sensor surface, multiple cycles of capture and elution allow the transfer and concentration of analyte into the elution buffer. The eluted analyte can be studied directly by MALDI-TOFMS, or subjected to proteolytic digestion for protein identification. Transfer into the elution buffer and MALDI-TOFMS detection was achieved from 5 [micro]L of starting samples containing