Direct electron transfer reactions between human ceruloplasmin and electrodes.

In an effort to find conditions favouring bioelectrocatalytic reduction of oxygen by surface-immobilised human ceruloplasmin (Cp), direct electron transfer (DET) reactions between Cp and an extended range of surfaces were considered. Exploiting advances in surface nanotechnology, bare and carbon-nanotube-modified spectrographic graphite electrodes as well as bare, thiol- and gold-nanoparticle-modified gold electrodes were considered, and ellipsometry provided clues as to the amount and form of adsorbed Cp. DET was studied under different conditions by cyclic voltammetry and chronoamperometry.

Analysis of triazines and associated metabolites with electrospray ionization field-asymmetric ion mobility spectrometry/mass spectrometry.

Triazines comprise an important pollutant class owing to continued use in certain countries, and owing to strong environmental persistence that leads to problems even in countries like Sweden where the use of triazines has been prohibited for some years. We investigated mass-selective detection for analysis of triazines. More specifically, we studied the background reduction and sensitivity enhancement that result from the use of a new interface technique, field-asymmetric ion mobility spectrometry (FAIMS), in conjunction with electrospray ionization ion-trap mass spectrometry.

Terbutaline enantiomer separation and quantification by complexation and field asymmetric ion mobility spectrometry-tandem mass spectrometry.

Recently, we introduced a new approach to chiral separation and analysis of amino acids by chiral complexation and electrospray high-field asymmetric waveform ion mobility spectrometry coupled to mass spectrometry (ESI-FAIMS-MS). In the present work, we extended this approach to the separation of the drug compound terbutaline. Terbutaline enantiomers were complexed with metal ions and an amino acid to form diastereomeric complexes of the type [M(II)(L-Ref)2((+)/(-)-A)-H](+), where M(II) is a divalent metal ion, L-Ref is an amino acid in its L-form, and A is the terbutaline analyte.

Electrospray ionization mass spectrometry in enzymology: uncovering the mechanisms of two-substrate reactions.

The purpose of this review is to draw attention to the use of electrospray ionization mass spectrometry (ESI-MS) for monitoring the course of enzyme-substrate interactions, in the particular case of complex systems in which two substrates participate. The determination and characterization of intra-molecular reactions, especially those that occur in the enzyme active site, is not a trivial task in chemical kinetics, typically requiring long measurement times and relatively expensive techniques such as nuclear magnetic resonance (NMR), X-ray crystallography or electron microscopy (EM). However, nowadays almost all laboratories are equipped with or else have access to the ESI-MS technique.

Enantiomer separation of amino acids by complexation with chiral reference compounds and high-field asymmetric waveform ion mobility spectrometry: preliminary results and possible limitations.

We present a new method for separation of enantiomers with high-field asymmetric waveform ion mobility spectrometry (FAIMS), coupled to mass spectrometric detection. Upon addition of an appropriate chiral reference compound to the analyte solution and subsequent ionization of the solution by electrospray ionization, analyte enantiomers formed diastereomeric complexes, which were potentially separable by FAIMS. The methodology being developed is intended to be general, but here amino acid analytes are specifically considered.

Characterization of two new multiforms of Trametes pubescens laccase.

Electrochemical properties of two multiforms of laccase from Trametes pubescens basidiomycete (LAC1 and LAC2) have been studied. The standard redox potentials of the T1 sites of the enzymes were found to be 746 and 738 mV vs. NHE for LAC1 and LAC2, respectively.

Extraction and preconcentration of salbutamol and terbutaline from aqueous samples using hollow fiber supported liquid membrane containing anionic carrier.

This paper presents a new three-phase liquid-phase microextraction (LPME) strategy for extraction and preconcentration of salbutamol (SB) and terbutaline (TB) from aqueous samples, including urine. The drugs were extracted from 11 ml of aqueous sample (source phase; SP) into an organic phase with microliter volume located inside the pores of a polypropylene hollow fiber, and then back-extracted into 24 microl of a second aqueous solution as the receiving phase (RP), located in the lumen of the hollow fiber. In preliminary experiments, we tried to transport the drugs using a pH gradient between the two sides of the hollow fiber.

Autoreduction and aggregation of fungal laccase in solution phase: possible correlation with a resting form of laccase.

This paper reports results of a reexamination of some poorly understood peculiarities of laccases, an enzyme family which has been extensively studied in our laboratories as well as by others for some years. The issue that is reconsidered here is the previously proposed existence of "active" and "resting" forms of laccases. The presence of fungal laccases with partly reduced active sites is demonstrated.

Metallation of the transition-state inhibitor N-methyl mesoporphyrin by ferrochelatase: implications for the catalytic reaction mechanism.

Insertion of metals into various tetrapyrroles is catalysed by a group of enzymes called chelatases, e.g. nickel, cobalt, magnesium and ferro-chelatase.

Microchip immobilized enzyme reactors for hydrolysis of methyl cellulose.

Microchip immobilized enzyme reactors (microIMERs) with immobilized endoglucanases were applied for the hydrolysis of methyl cellulose (MC). MCs of various molecular weights were hydrolyzed using two microIMERs containing immobilized celloendoglucanase Cel 5A from Bacillus agaradhaerens (BaCel 5A) connected in series. Hydrolysis by the microIMER could be confirmed from the average molar masses and molar mass distributions measured by size exclusion chromatography (SEC) with online multiangle light scattering and refractive index detection.