Search results for "macromolecular"
showing 10 items of 944 documents
Quantitative retention- and migration-toxicity relationships of phenoxy acid herbicides in micellar liquid chromatography and micellar electrokinetic…
2001
Abstract The need to obtain a tool for estimation of toxicity parameters for chemicals supports, the postulation of predictive models as an alternative to conventional classical assays. The use of micellar solutions of Brij35 as mobile phases in reversed phase liquid chromatography has proven to be valid in predicting some biological activities of different kinds of drugs. In this paper, the correlations between retention of phenoxy acids using different concentrations of Brij35 as micellar mobile phase in micellar liquid chromatography (MLC) and migration in micellar electrokinetic chromatography (MEKC) with several toxicity parameters are studied. Adequate correlations retention- and migr…
Keyhole limpet hemocyanin (KLH), I: Reassociation from Immucothel® followed by separation of KLH1 and KLH2
1997
Abstract Studies of keyhole limpet hemocyanin (KLH) normally require purification of functional complexes directly from living animals. An alternative procedure is described wherein a commercial preparation of KLH which is fully dissociated into its subunits (Immucothel®, biosyn Arzneimittel GmbH) is reassociated in the presence of a high concentration of calcium and magnesium. The reassociation products, when observed by electron microscopy, consist of didecamers, multidecamers and flexible tubules of varying length. The two forms of KLH described previously and designated KLH1 and KLH2, are present in the reassocated mixture as homo-oligomers/polymers and can be separated by selective dis…
High Submicellar Liquid Chromatography
2013
Surfactant addition above the critical micellar concentration (CMC), in reversed-phase liquid chromatography (RPLC), was proposed as a way to modify the selectivity and analysis time, giving rise to a chromatographic mode called micellar liquid chromatography (MLC). However, solutions containing only surfactant are too weak and yield poor peak shape. This was remediated by the addition of a small amount of organic solvent. To preserve the existence of micelles, in MLC high contents of organic solvent are avoided. Nevertheless, there is no reason to neglect the potentiality of mobile phases containing a surfactant above its CMC in water and a high organic solvent content (without micelles). …
Affinity chromatographic separation of plant lactate dehydrogenase
1978
Abstract Lactate dehydrogenase from potato tubers was purified by the use of several standard purification procedures as well as by affinity chromatography on C
Glucagon fibril polymorphism reflects differences in protofilament backbone structure
2010
Amyloid fibrils formed by the 29-residue peptide hormone glucagon at different concentrations have strikingly different morphologies when observed by transmission electron microscopy. Fibrils formed at low concentration (0.25 mg/mL) consist of two or more protofilaments with a regular twist, while fibrils at high concentration (8 mg/mL) consist of two straight protofilaments. Here, we explore the structural differences underlying glucagon polymorphism using proteolytic degradation, linear and circular dichroism, Fourier transform infrared spectroscopy (FTIR), and X-ray fiber diffraction. Morphological differences are perpetuated at all structural levels, indicating that the two fibril class…
Characterization of gramicidin A in an inverted micellar environment. A combined high-performance liquid chromatographic and spectroscopic study
1992
We have investigated the conformational adaptability of gramicidin A incorporated into reverse micelles of sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane/water, a so far unexplored "host" membrane-mimetic model system for this peptide. A high-performance liquid chromatographic strategy previously developed for the study of gramicidin in phospholipid vesicles and normal micelles [Bañó et al. (1989) FEBS Lett. 250, 67; Bañó et al. (1991) Biochemistry 30, 886] has been successfully extended to this system. The method has permitted the separation of peptide conformational species, namely, double-stranded dimers and monomers, and an accurate quantitation of their proportion in the invert…
Dynamic Light Scattering Investigation of the Kinetics and Fidelity of Supramolecular Copolymerizations in Water
2017
The self-assembly of supramolecular copolymers facilitates the preparation of multifunctional materials, with tunable mechanical, electronic, or bioactive properties. Compared to covalent copolymerization protocols, controlling the molecular weight, stability, and monomer sequence of a multicomponent supramolecular copolymer remains limited. Here, we report a light scattering investigation of the charge-regulated supramolecular copolymerization in neutral buffer of physiological ionic strength, supported with electron microscopy and circular dichroism spectroscopy experiments. Dendritic anionic and cationic peptide comonomers self-assemble into AB-type heterocopolymers with a nanorod-like m…
Characterization of the interaction between Actinin-Associated LIM Protein (ALP) and the rod domain of α-actinin
2009
Abstract Background The PDZ-LIM proteins are a family of signalling adaptors that interact with the actin cross-linking protein, α-actinin, via their PDZ domains or via internal regions between the PDZ and LIM domains. Three of the PDZ-LIM proteins have a conserved 26-residue ZM motif in the internal region, but the structure of the internal region is unknown. Results In this study, using circular dichroism and nuclear magnetic resonance (NMR), we showed that the ALP internal region (residues 107–273) was largely unfolded in solution, but was able to interact with the α-actinin rod domain in vitro, and to co-localize with α-actinin on stress fibres in vivo. NMR analysis revealed that the ti…
Calorimetric and structural investigation of the interaction between bovine serum albumin and high molecular weight dextran in water.
2005
This work studies specific interactions between a small globular protein and a highly flexible, branched polysaccharide using differential scanning calorimetry (DSC), circular dichroism (CD), fluorescence, and turbidimetry measurements. It uses the system water/bovine serum albumin (BSA)/dextran (D 2000) as a model. Dextran molecules are able to form interpolymeric complexes with BSA in water at both low and high temperatures if the polysaccharide is in excess and if the protein exists in its associated state. It leads to a partial destabilization of the secondary and tertiary structures of the protein and an additional exposure of the hydrophobic tryptophan residues to the surface of globu…
Supramolecular polymerization of sulfated dendritic peptide amphiphiles into multivalent L-selectin binders
2021
The synthesis of a sulfate-modified dendritic peptide amphiphile and its self-assembly into one-dimensional rod-like architectures in aqueous medium is reported. The influence of the ionic strength on the supramolecular polymerization was probed via circular dichroism spectroscopy and cryogenic transmission electron microscopy. Physiological salt concentrations efficiently screen the charges of the dendritic building block equipped with eight sulfate groups and trigger the formation of rigid supramolecular polymers. Since multivalent sulfated supramolecular structures mimic naturally occurring L-selectin ligands, the corresponding affinity was evaluated using a competitive SPR binding assay…