[Show abstract][Hide abstract] ABSTRACT: The coupling of the techniques, high-performance liquid chromatography (HPLC), orthogonal acceleration time-of-flight mass spectrometry (OATOF-MS) and inductively coupled plasma mass spectrometry (ICP-MS) provides a very powerful method for identifying and quantifying the products of bradykinin metabolism. In this study, we were able to identify the major metabolites of bradykinin degradation reported in the literature. In addition, a new bradykinin metabolite corresponding to bradykinin 5,9 fragment (BK-(5,9)-fragment) was identified as a product of neutral endopeptidase (NEP) activity. This finding establishes that NEP cleaves bradykinin simultaneously at the positions 4-5 and 7-8. We also demonstrate the equivalent participation of NEP and angiotensin-converting enzyme (ACE) within the rat lung tissue membranes (RLTM) in bradykinin degradation, suggesting its suitability as a model for the assay of dual ACE/NEP inhibitors. On the contrary, in rat kidney brush border membranes (KBBM), ACE is not significantly involved in bradykinin metabolism, with NEP being the major enzyme.
No preview · Article · Mar 2006 · Journal of Peptide Science
[Show abstract][Hide abstract] ABSTRACT: Both LC and capillary LC (CapLC) have been successfully interfaced with inductively coupled plasma mass spectrometry (ICP-MS). Gradients of acetonitrile and aqueous based solvents have been employed to separate several compounds of pharmaceutical interest. This paper will describe four application areas in the pharmaceutical industry, and examples will be shown where CapLC, LC and gel electrophoresis via laser ablation have been coupled with ICP-MS. The four areas highlighted in this paper are: (1) the use of derivatisation reactions to "make the invisible visible". Methods involving derivatisations with copper and iron will be described that can be used for the analysis of amines and carboxylic acids by ICP-MS. (2) The profiling of metal ion content (in particular bromine) in biological samples such as human plasma, this study will focus on the metabolism of bromine-labelled peptides (e.g. substance P). (3) The analysis of materials derived from single, solid-phase beads used in combinatorial chemistry, and (4) also discussed will be our findings from investigations into the use of laser ablation ICP-MS on the determination of protein phosphorylation on electrophoresis gel blots.
No preview · Article · Dec 2004 · Journal of Chromatography A