Purification of the specific immunoglobulin G1 by immobilized metal ion affinity chromatography using nickel complexes of chelating porous and nonporous polymeric sorbents based on poly(methacrylic esters). Effect of polymer structure

Ni2+ complexes of the chelating nonporous and porous bead sorbents based on methacrylic esters crosslinked with ethylene dimethacrylate were used in isolation of the horseradish peroxidase-specific immunoglobulin IgG1 from the crude mouse ascitic fluid by immobilized metal ion affinity chromatography (IMAC). Iminodiacetic and aspartic acids were attached to porous poly(glycidyl methacrylate) beads differing in size, morphology and chemical composition. Ethylenediaminetriacetic acid and quinolin-8-ol chelating groups were attached mainly to the surface hydroxyl groups in nonporous poly(diethylene glycol methacrylate) beads through spacers. The latter sorbents exhibited better kinetic characteristics than the former but a very low IgG1 sorption capacity. In a single-step IMAC procedure, the best efficiency in the specific IgG1 purification was obtained with porous sorbents (recovery 92%, purity 73%). Differences in IMAC separations are discussed from the point of view of morphology of polymer beads as well as of the type and concentration of chelating ligands.     

Chemiluminescence determination of antibacterial drug trimethoprim by automated sequential injection technique with permanganate and hexametaphosphate as reagents

Antibacterial drug trimethoprim [2,4-diamino-5-(3,4,5-trimethoxybenzyl)-pyrimidine] (I) was determined in pharmaceutical formulations by using a lab-made PC-controlled SIA analyser linked to conventional HPLC fluorimetric detector equipped with a chemiluminescence module. The chemical principle is the oxidation of I by KMnO(4) in acid medium; the reaction is accompanied by the emission of chemiluminescence, which is enhanced in the presence of hexametaphosphate (HMP). The optimum sequence and the flow parameters and concentrations and volumes of reagents aspirated optimised by a computer-aided simplex method were, 100 mul of 5 mM HMP, 40 mul of a test solution of I, 2 mul of 0.5 M H(2)SO(4) and 20 mul of 1 mM KMnO(4); the luminescing zone was pushed into the detector at a flow rate of 49 mul s(-1). The calibration graph relating the intensity of luminescence to concentration of I was parabolic (r=0.9994) in the range 0.5-100 mug ml(-1) of I with rectilinear part (r=0.9999) in the range 20-100 mug ml(-1) of I; the limit of detection was 0.1 mug ml(-1) of I. The method was used for the assay of Triprim(R) tablets (with nominal content 100 or 200 mg of I) for the active substance as well as for content uniformity tests; the R.S.D. values did not exceed 1% (n=5). The SIA results did not show statistical difference from those obtained by pharmacopoeial acidimetric titration in non-aqueous medium; the excipients such as microcrystalline cellulose, maze starch, povidone, talc, magnesium stearate and gelatin did not interfere.     

Optical trapping of nanoparticles and microparticles by a Gaussian standing wave

The optical trapping of nanoparticles and microparticles by a Gaussian standing wave is experimentally demonstrated for the first time to the authors' knowledge. The standing wave is obtained under a microscope objective as a result of the interference of an incoming laser beam and a beam reflected on a microscope slide that has been coated with a system of reflective dielectric layers. Experimental results show that three-dimensional trapping of nanoparticles (100-nm polystyrene spheres) and one or more vertically aligned micro-objects (5-mum polystyrene spheres, yeast cells) can easily be achieved by use of even highly aberrated beams or objectives with low numerical apertures.     

A mean value theorem on bounded symmetric domains

Let be a Cartan domain of rank and genus and , , the Berezin transform on ; the number can be interpreted as a certain invariant-mean-value of a function around . We show that a Lebesgue integrable function satisfying , , must be -harmonic. In a sense, this result is reminiscent of Delsarte's two-radius mean-value theorem for ordinary harmonic functions on the complex -space , but with the role of radius played by the quantity .

     

Geometry of the numerical range of matrices

Some techniques for the study of the algebraic curve C(A) which generates the numerical range W(A) of an n×n matrix A as its convex hull are developed. These enable one to give an explicit point equation of C(A) and a formula for the curvature of C(A) at a boundary point of W(A). Applied to the case of a nonnegative matrix A, a simple relation is found between the curvature of the function Φ(A)=p((1?α)A+ αA^T) (pbeingthePerronroot) at $\text{α=}\text{1}\text{2}$ and the curvature of W(A) at the Perron root of $\text{1}\text{2}\text{(A+A}{}^{\mathrm{T}}\text{)}$. A connection with 2-dimensional pencils of Hermitian matrices is mentioned and a conjecture formulated.     

Applications of NMR spectroscopy of chiral association complexes. 6. rotation about the C(sp2)—C(aryl) bond in 2,6-disubstituted pivalophenones

For the investigation of the barrier to rotation about the C(sp²)—C(aryl) bond in non-planar pivalophenones five derivatives were prepared and their ¹H and ¹³C NMR spectra assigned. Methyl and bromine groups in the 3-position have opposite substituent effects on the chemical shifts of the ¹H and ¹³C signals of Me² and Me⁴. The ΔG values were determined from the coalescence temperatures of the signal splittings generated by the addition of optically active shift reagents. The accuracy of this method was estimated by using different signals of 3-bromo-2,4,6-trimethylpivalophenone and by computer simulation of the line shape. A buttressing effect of substituents in the aromatic ring was observed. A change of the twist angle by the substitution of methyl by bromine in the tert-butyl group was suggested in order to explain the changes in ΔG and the chemical shifts.     

Wetting films of lipids in the development of sensitive interfaces. An electrochemical approach

Solid-supported thin liquid films of lipids, contacting an electrolyte phase, turned out to be a dependable system in the field of bosensors. The investigations of these objects during the past decade reveal some of their intriguing features enabling the application in constructions of receptor part with 'two-dimensional' arrangement. As a model system, complementary to the other artificial analogs of biomembranes, the wetting films of lipids offer certain advantages concerning the compromise between the stability and flexibility of the molecular structures involved in sensing. The basic principles underlaying the techniques of formation, as well as the conditions of the films stability are emphasized in the present consized review. While no limitations are imposed by the way of preparation, the films seem especially profitable in conjunction with methods for electrochemical signal transduction. In this regard some prominent examples are discussed.     

Congruence-preserving functions on Stone and Kleene algebras

We investigate local polynomial functions on Stone algebras and on Kleene algebras. We find a generating set for the clone of all local polynomial functions. We also represent local polynomial functions on a given algebra by polynomial functions of some canonical extension of this algebra.     

Lineshapes of spin exchange broadened EPR spectra

An unexplained residual in the fits of theoretical and experimental spectra of exchange broadened nitroxide spin probes reported by Robinson et al. [J. Magn. Reson. 138 (1999) 199] is shown to be understood by inclusion of theoretically predicted lineshape changes into the fitting routine. These lineshape changes provide an additional estimate of the spin exchange frequency that is independent of linewidth methods.     

A general synthesis of water soluble upper rim calix[n]arene guanidinium derivatives which bind to plasmid DNA

The reaction of O-alkylated p-aminocalix[n]arenes (n=4, 6, 8) with N,N′-di(tert-butoxycarbonyl)thiourea in the presence of HgCl₂ and subsequent removal of the protective groups with hydrochloric acid led to the new water soluble calix[n]guanidinium derivatives (p-guanidiniumcalix[n]arenes) 20-23. With the exception of tetraoctyl-p-guanidiniumcalix[4]arene 21, which forms a macroscopic gelatinous aggregate even at very low concentration, all the synthesised guanidinium calixarenes show good solubility in water and sharp NMR signals. Moreover, these compounds are not cytotoxic and bind to plasmid DNA.