Strategies for capillary electrophoresis: Method development and validation for pharmaceutical and biological applications—Updated and completely revised edition

This review is in support of the development of selective, precise, fast, and validated capillary electrophoresis (CE) methods. It follows up a similar article from 1998, Wätzig H, Degenhardt M, Kunkel A. “Strategies for capillary electrophoresis: method development and validation for pharmaceutical and biological applications,” pointing out which fundamentals are still valid and at the same time showing the enormous achievements in the last 25 years. The structures of both reviews are widely similar, in order to facilitate their simultaneous use. Focusing on pharmaceutical and biological applications, the successful use of CE is now demonstrated by more than 600 carefully selected references. Many of those are recent reviews; therefore, a significant overview about the field is provided. There are extra sections about sample pretreatment related to CE and microchip CE, and a completely revised section about method development for protein analytes and biomolecules in general. The general strategies for method development are summed up with regard to selectivity, efficiency, precision, analysis time, limit of detection, sample pretreatment requirements, and validation.     

Laccase of Coriolus zonatus

Laccase is one of the lignolytic enzymes found in liquid cultures of the fungus Coriolus zonatus in defined medium. The enzyme was isolated from culture liquid and characterized. Laccase from C. zonatus is a single-chain protein with a molecular mass of 60 kDa. Carbohydrate moiety of enzyme consisted of mannose, galactose and N-acetyl-glucosamine in a ratio of 6:2:0,6 respectively, and comprised 10% of the entiremolecule lsoelectric point was detected at pH 4.6. Laccase was found to have a pH optimum of 4.9 and temperature optimum of 55°C. Substrate specificity studies were conducted with catechol, K-ferrocyanide, hydroquinone, and sinapinic acid as substrates. The highest efficiency of catalysis was observed with sinapic acid as the substrate. The kinetic constants k _cat and K₂₈ of this reaction were 624 s⁻¹ and 7 μM, respectively.     

Photochemical reactions. 140th Communication. Acid-catalyzed rearrangement and electron transfer photooxygenation of cyclopropanols and their silyl ethers

On acid-catalyzed hydrolysis, the tricyclic compounds 2 and 10 , incorporating cyclopropyl-silyl-ether moieties undergo rearrangement to the cis-decalones 3 and 7 , respectively. Hydrolysis of 2 and 10 in the presence of oxygen leads additionally to the formation of the 1,2-dioxolan-3-ols 9 and 13 , respectively, which involves an electron-transfer oxygenation process as could be demonstrated by photooxygenation of the silyl ether 10 and the cyclopropanol 14 in the presence of 9,10-dicyanoanthracene. The configurations of 3 and 9 were assigned by X-ray analysis of the latter compound as well as of the p-nitrobenzoate 8 of 3 .     

Glucose oxidase—hexokinase bienzyme electrode sensor for adenosine triphosphate

A bienzyme electrode, based on the oxygen electrode, and containing immobilized glucose oxidase and hexokinase is described for the measurement of 0.2–3 mM adenosine triphosphate.     

Self-assembly of S-layer-enveloped cytochrome c polyelectrolyte multilayers

We report a study of the electrostatic layer-by-layer self-assembly of electroactive polyelectrolyte multilayers incorporating the redox protein cytochrome c (cyt c) combined with recrystallization of the bacterial cell wall surface layer from Bacillus sphaericus CCM 2177 SbpA (S-layer). The polyelectrolyte multilayer assembly was prepared on flat gold electrodes with a nanometer-scale roughness that allowed monitoring of the film formation throughout all the assembly stages by atomic force microscopy measurements in liquid with respect to topography and forces. The deposition of alternating layers of sulfonated polyaniline and cyt c was carried out by adsorption from the corresponding solutions on a cyt c monolayer electrode. The electroactivity of cyt c within the assembly was confirmed by cyclic voltammetry. We showed that the surface properties of the electrode terminating layer change after each adsorption step accordingly. We also found that S-layer recrystallization on the top of the multilayer film was feasible while electroactivity of cyt c within a polyelectrolyte matrix was partially maintained. This approach offers a new strategy to design a biocompatible and permselective outer envelope of a polyelectrolyte multilayer, promising sensor applications.     

Lithiated Azafulvenes by Halogen/Metal Interchange of Brominated 6-(Diisopropylamino)-1-azafulvene Derivatives. Novel synthesis of 5-mono- and 4,5-disubstituted 1H-pyrrole-2-carbaldehydes

The first known lithiated 1-azafulvene derivatives were generated by low-temperature halogen/metal interchange, with t-BuLi, from the corresponding brominated 6-diisopropylamino compounds 3b and 12 . These Li species reacted with sundry eletrophilic reagents to give products which, on basic hydrolysis, were converted into 5-mono- or 4,5-disubstituted pyrrole-2-carbaldehydes 10 and 16 , respectively.