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Biomedical subjects

Andreas Prange

Publications and source records attributed to Andreas Prange.

10 recordsLinked to original sources
PubMed2005

Distribution of elements binding to molecules with different molecular weights in aqueous extract of Antarctic krill by size-exclusion chromatography coupled with inductively coupled plasma mass spectrometry.

The distribution of silver, arsenic, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead, selenium and zinc binding to species with different molecular weight in aqueous extract of krill was studied by on-line size-exclusion chromatography (SEC)/inductively coupled plasma mass spectrometry (ICP-MS). The extract was fractionated in three fractions with different molecular weight (MW) ranges (>20,000 relative molecular mass (rel. mol. mass), 2000-20,000 rel. mol. mass and <2000 rel. mol. mass), which were further analyzed by SEC with columns having different optimum fractionation ranges in order to obtain more detailed information about the MW distribution of the elements. Various distribution profiles for the target elements among different MW ranges were observed. The results obtained indicated that manganese, zinc, silver, cadmium and lead species were mostly distributed in the higher MW range (>20,000 rel. mol. mass). In the case of chromium, iron, cobalt, arsenic and selenium, most of them bind to species with lower MW (<2000 rel. mol. mass). Only copper and nickel species was predominantly present in middle MW range (2000-20,000 rel. mol. mass). Further speciation of arsenic compounds in the small MW fraction was carried out with anion exchange chromatography (AEC) coupled with ICP-MS. The results showed that the dominant arsenic species in this fraction is As(III) (63% of extractable arsenic), while As(V) (13%) and two unknown arsenic species (19% and 5%, respectively) are present in lower amounts.

Animals↗
PubMed2004

Development and characterisation of a new interface for coupling capillary LC with collision-cell ICP-MS and its application for phosphorylation profiling of tryptic protein digests.

A comparison of different nebulisers for direct hyphenation of capillary and nano liquid chromatography (Cap-LC, Nano-LC) and quadrupole-based collision cell inductively coupled plasma mass spectrometry (CC-ICP-MS) for phosphorylation profiling of tryptic protein digests is described. Helium was used as cell gas and specially tuned instrumental conditions were used to achieve background minimisation at the mass of phosphorus, because of kinetic energy discrimination of the interfering polyatomic ions. The proposed set-up is based on a modified capillary electrophoresis interface and a home-made 4 mL spray chamber. It enables the use of gradient conditions with a highly concentrated organic mobile phase as often used in protein phosphorylation analysis, without the need to apply membrane desolvation for removal of the organic phase or further background minimisation. No significant signal suppression or other negative effects caused by the organic mobile phase occur, because of the low flow rates used in Cap-LC and the robust plasma conditions of the CC-ICP-MS instrument. A tryptic digest of beta-casein was investigated as model compound to demonstrate the applicability of the proposed set-up for phosphorylation profiling in protein analysis using quadrupole based collision-cell ICP-MS as phosphorus-specific detector. Detection limits for phosphorylated peptides down to the sub picomole level were obtained. As a complementary technique, electrospray ionisation tandem mass spectrometry (ESI-MS-MS) with data base searching was used for further characterisation of the phosphorylated peptides detected.

Chromatography, Liquid↗
PubMed2004

Determination of the absolute configuration of selenomethionine from antarctic krill by RP-HPLC/ICP-MS using chiral derivatization agents.

A fast and sensitive method was developed for the determination of the absolute configuration of selenomethionine. The enantiomers of selenomethionine were converted into diastereomeric isoindole derivatives by reaction with o-phthaldialdehyde and N-isobutyryl-L-cysteine. This easy-to-handle reaction proceeds quantitatively in a few minutes at room temperature. Separation and detection of the diastereomers was achieved by reversed-phase high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (RP-HPLC/ICP-MS) using a conventional C18 reversed-phase column. Detection limits of about 4 microg L(-1) were obtained. The method was applied to the determination of the configuration of selenomethionine extracted from antarctic krill, which turned out to possess the L-configuration.

Animals↗
PubMed2003

Determination of sulfur and selected trace elements in metallothionein-like proteins using capillary electrophoresis hyphenated to inductively coupled plasma mass spectrometry with an octopole reaction cell.

The determination of sulfur in biologically relevant samples such as metalloproteins is described. The analytical methodology used is based on robust on-line coupling between capillary electrophoresis (CE) and octopole reaction cell inductively-coupled plasma mass spectrometry (ORC-ICP-MS). Polyatomic ions that form in the plasma and interfere with the determination of S at mass 32 are minimised by addition of xenon to the collision cell. The method has been applied to the separation and simultaneous element-specific detection of sulfur, cadmium, copper, and zinc in commercially available metallothionein preparations (MT) and metallothionein-like proteins (MLP) extracted from liver samples of bream ( Abramis brama L.) caught in the river Elbe, Germany. Instrumental detection limits have been calculated according to the German standard procedure DIN 32645 for the determination of sulfur and some simultaneously measured trace elements in aqueous solution. For sulfur detection limits down to 1.3 microg L(-1) ((34)S) and 3.2 microg L(-1) ((32)S) were derived. For the other trace elements determined simultaneously detection limits ranging from 300 ng L(-1) ((58)Ni) to 500 ng L(-1) ((66)Zn, (55)Mn) were achieved. For quantification of sulfur and cadmium in a commercially available MT preparation under hyphenated conditions the use of external calibration is suggested. Finally, the need for proper sample-preparation technique will be discussed.

Animals↗
PubMed2003

CZE-ICP-MS separation of metallothioneins in human brain cytosols: comparability of electropherograms obtained from different sample matrices.

Capillary zone electrophoresis, with its high resolution capability in the separation of different compounds, is well suited for the investigation of metal-containing proteins, especially when elemental detection is conducted using hyphenated inductively coupled plasma-mass spectrometry. A major problem in the separation of proteins in body fluids is caused by the effects of different sample matrix composition. The migration time of proteins varies significantly, depending on the nature of the matrix. Electropherograms are consequently difficult to compare and the peak identification is uncertain. Pre-analytical steps for the reduction of matrix compounds enhance the quality of the data, but the results are still unsatisfactory. This paper describes a technique for obtaining electropherograms that can be used for comparison purposes by correction of the data with the aid of time markers. A mixture of five substances (caesium chloride, arsenocholine, arsenobetaine, dimethylarsinic acid and monomethylarsonic acid) was added in a separate injection step. Ionic caesium eluted at the start of the separation and the other four markers appeared throughout and at the end of the electropherogram. All electropherograms were normalized to a reference run by recalculation of the time axis using the time markers. The method was applied to the analysis of human brain cytosols. Samples were separated after different pre-treatment steps and were compared, with special emphasis on the detection of the isoform metallothionein-3.

Brain Chemistry↗
PubMed2002

Hyphenated techniques for the characterization and quantification of metallothionein isoforms.

Recent developments in the coupling of highly selective separation techniques such as capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) to element-specific and molecule-specific detectors, such as inductively-coupled plasma mass spectrometry (ICP-MS) and electrospray ionization-tandem mass spectrometry (ESI-MS/MS) for the characterization and quantification of metallothioneins (MTs) are critically reviewed and discussed. This review gives an update based on the literature over the last five years. The coupling of CE to ICP-MS is especially highlighted. As a result of progress in new interface technologies for CE-ICP-MS, research topics presented in the literature are changing from "the characterization of interfaces by metallothioneins" to the "characterization of metallothioneins by CE-ICP-MS". New applications of CE-ICP-MS to the analysis of MTs in real samples are summarized. The potential of the on-line isotope dilution technique for the quantification of MTs and for the determination of the stoichiometric composition of metalloprotein complexes is discussed. Furthermore, a selection of relevant papers dealing with HPLC-ICP-MS for MT analysis are summarized and compared to those dealing with CE-ICP-MS. In particular, the use of size-exclusion (SE)-HPLC as a preliminary separation step for metallothioneins in real samples prior to further chromatographic or electrophoretic separations is considered. Additionally, the application of electrospray ionisation-tandem mass spectrometry (ESI-MS/MS) for the identification of metallothionein isoforms following electrophoretic or chromatographic separation is discussed.

Animals↗
PubMed2002

Use of surface-modified capillaries in the separation and characterization of metallothionein isoforms by capillary electrophoresis inductively coupled plasma mass spectrometry.

The separation of metallothionein (ML) isoforms using capillary electrophoresis (CE) has been improved by applying surface-modified capillaries, and the metal composition of MTs has been characterized by subsequent inductively coupled plasma sector field mass spectrometry (ICPSFMS). Nine MT complexes in a commercial preparation from rabbit liver were successfully separated on an anionic polymer-coated column, prepared by immobilizing poly(2-acrylamido-2-methyl-1-propanesulfonic acid) on the fused-silica surface via a linking agent. On uncoated capillaries or those coated dynamically with cationic materials, only three complexes could be separated. Online isotope dilution analysis combined with CE/ICPSFMS indicated the stoichiometric molar metal contents in the MT complexes.

Animals↗
PubMed2001

Characterization and quantification of metallothionein isoforms by capillary electrophoresis-inductively coupled plasma-isotope-dilution mass spectrometry.

In a new approach to the characterization and quantification of metallothionein isoforms an on-line isotope-dilution method in combination with the coupling of capillary electrophoresis (CE) to an inductively coupled plasma-sector field mass spectrometer (ICP-SFMS) is reported. Metallothionein (MT) isoforms are separated by CE and the elements Cu, Zn, Cd, and S are detected simultaneously by use of ICP-SFMS in the medium resolution mode. On-line isotope dilution is performed by continuous introduction of an isotopically enriched, species-unspecific spike solution after the separation step. MT from rabbit liver and a further purified MT-1 isoform were quantified by determination of sulfur, and the stoichiometric compositions of the metalloprotein complexes are characterized by determination of their sulfur-to-metal ratios.

Algorithms↗