Development of a sensitive method for the determination of acrylamide in coffee using high-performance liquid chromatography coupled to a hybrid quadrupole Orbitrap mass spectrometer.

The emerging trend towards high-resolution mass spectrometry (MS) alternatives was evaluated by the application of Orbitrap MS for the determination of acrylamide in coffee samples. The high resolving power of the Orbitrap MS provided the high selectivity and sensitivity that enabled quantitative analysis of acrylamide in complex matrices, such as coffee. Several sample preparation methods and scanning modes of the MS (full MS, t-SIM, t-MS2) were assessed in order to optimise parameters of the analytical method.

Evaluating the potential of vacuolar ATPase inhibitors as anticancer agents and multigram synthesis of the potent salicylihalamide analog saliphenylhalamide.

The natural product salicylihalamide is a potent inhibitor of the Vacuolar ATPase (V-ATPase), a potential target for antitumor chemotherapy. We generated salicylihalamide-resistant tumor cell lines typified by an overexpansion of lysosomal organelles. We also found that many tumor cell lines upregulate tissue-specific plasmalemmal V-ATPases, and hypothesize that tumors that derive their energy from glycolysis rely on these isoforms to maintain a neutral cytosolic pH.

A tagging-via-substrate technology for detection and proteomics of farnesylated proteins.

A recently developed proteomics strategy, designated tagging-via-substrate (TAS) approach, is described for the detection and proteomic analysis of farnesylated proteins. TAS technology involves metabolic incorporation of a synthetic azido-farnesyl analog and chemoselective derivatization of azido-farnesyl-modified proteins by an elegant version of Staudinger reaction, pioneered by the Bertozzi group, using a biotinylated phosphine capture reagent. The resulting protein conjugates can be specifically detected and/or affinity-purified by streptavidin-linked horseradish peroxidase or agarose beads, respectively.

Selective enrichment of thiophosphorylated polypeptides as a tool for the analysis of protein phosphorylation.

A chemoselective alkylation method is described for the isolation and subsequent identification of thiophosphorylated peptides/proteins. The method involves thiophosphorylation of proteins using adenosine 5'-O-(thiotriphosphate) (ATPgammaS) followed by selective in situ alkylation of the newly thiophosphorylated proteins resulting in a stable covalent bond. The chemoselective alkylation exploits the relatively high nucleophilicity at low pH of the sulfur in thiophosphate residues, whereas the nucleophilicities of phosphates, amines, and other functionality of amino acids are negligible or significantly suppressed.