Characterization of Trypanosoma brucei gambiense variant surface glycoprotein LiTat 1.5

At present, all available diagnostic antibody detection tests for Trypanosoma brucei gambiense human African trypanosomiasis are based on predominant variant surface glycoproteins (VSGs), such as VSG LiTat 1.5. During investigations aiming at replacement of the native VSGs by recombinant proteins or synthetic peptides, the sequence of VSG LiTat 1.5 was derived from cDNA and direct N-terminal amino acid sequencing. Characterization of the VSG based on cysteine distribution in the amino acid sequence revealed an unusual cysteine pattern identical to that of VSG Kinu 1 of T. b. brucei. Even though both VSGs lack the third of four conserved cysteines typical for type A N-terminal domains, they can be classified as type A

Use of potentiometric detection in (ultra) high performance liquid chromatography and modelling with adsorption/desorption binding kinetics

Observation of a potentiometric sensor's response behaviour after injection in flow injection analysis at different concentrations allowed studying "on" and "off" kinetics of the analyte's adsorption/diffusion behaviour. The alkaloid metergoline was mostly used as an example. k(on) and k(off) rate constant values were measured, and the association constant K(ass), and ΔG values of the analyte-surface interaction were calculated with an adsorption-based model which proved to be fully applicable. k(on) increased by decreasing the sensor dimensions, while koff was unaffected by miniaturization. Increasing acetonitrile concentrations in the running buffer increased k(off), while k(on) was unaffected. The experimentally determined ΔG values of the analyte-surface interaction showed a linear relation to the response of the sensor, in mV. This knowledge was applied to optimize the potentiometric detection of plant alkaloids in (U)HPLC. Sub-micromolar detection limits were obtained with the potentiometric detector/(U)HPLC combination. This is the first time that the response rates and the response itself can be modelled accurately for coated wire potentiometric sensors, and it is the first application of a potentiometric detector in UPLC.publisher: Elsevier articletitle: Use of potentiometric detection in (ultra) high performance liquid chromatography and modelling with adsorption/desorption binding kinetics journaltitle: Analytica Chimica Acta articlelink: http://dx.doi.org/10.1016/j.aca.2013.03.031 content_type: article copyright: Copyright © 2013 Elsevier B.V. All rights reserved.status: publishe