Triterpenes are structurally complex plant natural products with numerous medicinal applications. They are synthesized through an origami-like process that involves cyclization of the linear 30 carbon precursor 2,3-oxidosqualene into different triterpene scaffolds. Here, through a forward genetic screen in planta, we identify a conserved amino acid residue that determines product specificity in...

Electrospray ionization (ESI) mass spectrometry was applied to the structural analysis of 23 2,6-[bis(alkyloxy)methyl]phenyltin(IV) derivatives. The mass spectra were measured in both polarity modes and multistage tandem mass spectrometric (MS(n)) measurements were performed on the ion trap analyser for positively charged tin-containing ions. The sum of complementary ions observed in the positi...

The cross-linking Mass Spectrometry (XL-MS) technique has enormous potential for studying the interactions between proteins, and it can provide detailed structural information about the interaction interfaces in large protein complexes. Such information has been difficult to obtain by conventional structural methods. One of the primary impediments to the wider use of the XL-MS technique is the ...

Unambiguous identification of tandem mass spectra is a cornerstone in mass-spectrometry-based proteomics. As the study of post-translational modifications (PTMs) by means of shotgun proteomics progresses in depth and coverage, the ability to correctly identify PTM-bearing peptides is essential, increasing the demand for advanced data interpretation. Several PTMs are known to generate unique fra...

The metabolism of arbidol in humans was studied using liquid chromatography-electrospray ionization (ESI) ion trap mass spectrometry (ITMS) after an oral dose of 300-mg arbidol. A total of 17 metabolites were identified including the glucuronide arbidol and the glucuronide sulfinylarbidol as the major metabolites. Arbidol and its metabolites have some common fragmentation patterns as a result o...

Background: Are dietary patterns, substantiated by biomarkers, associated with semen quality? Materials and Methods: In 161 men of subfertile couples undergoing in vitro fertilization treatment in a tertiary referral clinic in Rotterdam, the Netherlands, we assessed nutrient intakes and performed principal component factor analysis to identify dietary patterns. Total homocysteine (tHcy), folate...

The chemical cross-linking/mass spectrometry (MS) approach is gaining increasing importance as an alternative method for studying protein conformation and for deciphering protein interaction networks. This study is part of our ongoing efforts to develop innovative cross-linking principles for a facile and efficient assignment of cross-linked products. We evaluate two homobifunctional, amine-rea...

We report on a new approach for studying fragmentation channels in Proton Transfer Reaction-Mass Spectrometry (PTR-MS), which we name primary ion depletion kinetics (PIDK). PTR-MS is a chemical ionization mass spectrometric (CIMS) technique deploying hydronium ions for the chemical ionization. Induced by extremely high concentrations of analyte M, depletion of the primary ions in the drift tube...

Structural characterization and identification of components of complex biological mixtures constitutes one of the central aspects of metabolomics. Metabolite identification is a challenging but essential task in studies of biological samples. Mass spectrometry, because of its high sensitivity and specificity, is widely and successfully used in analysis of biological samples. Identification of ...

Sea cucumbers belonging to echinoderm are traditionally used as tonic food in China and other Asian countries. They produce abundant biologically active triterpene glycosides. More than 300 triterpene glycosides have been isolated and characterized from various species of sea cucumbers, which are classified as holostane and nonholostane depending on the presence or absence of a specific structu...