Charge-state and charge-continuum models in electrophoresis and isoelectric focusing of genetic variants

Nanospheres encapsulating anti-leishmanial drugs for their specific macrophage targeting, reduced toxicity, and deliberate intracellular release

The current work focuses on the study of polymeric, biodegradable nanoparticles (NPs) for the encapsulation of doxorubicin and mitomycin C (anti-leishmanial drugs), and their efficient delivery to macrophages, the parasite's home. The biodegradable polymer methoxypoly-(ethylene glycol)-b-poly (lactic acid) (MPEG-PLA) was used to prepare polymeric NPs encapsulating doxorubicin and mitomycin C. The morphology, mean diameter, and surface area of spherical NPs were determined by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and BET surface area analysis. X-ray diffraction was performed to validate drug encapsulation. An in vitro release profile of the drugs suggested a fairly slow release. These polymeric NPs were efficiently capable of releasing drug inside macrophages at a slower pace than the free drug, which was monitored by epi-fluorescence microscopy. Encapsulation of doxorubicin and mitomycin C into NPs also decreases cellular toxicity in mouse macrophages (J774.1A).

Human skeletal muscle myosin light chains analyzed by immobilized pH gradients during ontogenesis: identification of new phosphorylatable isoforms of light chain 2

Previous studies using two-dimensional gel electrophoresis have described adult and fetal isoforms of skeletal muscle myosin light chains (MLC). They have also revealed an embryo-specific light chain (LC1emb), apparently absent in most adult skeletal muscles. In order to characterize more thoroughly the MLC family, we have analyzed the MLCs from human skeletal muscle at different developmental stages using a two-dimensional electrophoresis technique with an immobilized pH gradient in the first dimension. The high resolution of this novel technique, resolving components which in isoelectric points are less than or equal to 0.01 pH, combined with sensitive silver staining, has allowed us to identify four phosphorylatable isoforms of MLC2: two slow-myosin light chains (MLC2Sa and b), two fast myosin light chains (MLC2Fa and b), and their phosphorylated counterparts: MLC2SaP and bP, MLC2FaP and bP. The following major modifications during development were observed: (i) The embryonic LC (LC1emb) persists up to at least 26 weeks of fetal life. (ii) The polymorphism of LC2 is already evident at 10 weeks of development but only the nonphosphorylated forms of LC2S and LC2F seem to be present. The LC2Fa form is predominant. As early as 26 weeks of fetal life, the 4 phosphorylated forms are detected. In the adult, LC2Fb is a minor component. (iii) LC3F (fast) is already expressed at an early embryonic stage (10 weeks).

Heterogeneous nature of human complement factor B: an electrophoretic approach for the analysis of its oligosaccharide chain structure and its physiological breakdown products

Factor B is a glycoprotein which plays an essential role in the alternative pathway of complement activation. It carries the proteolytic activity of the convertases, and its physiological breakdown products Ba and Bb have some effects on the cells of the immune system. Human factor B exhibits a microheterogeneity and five isoforms are present in serum. The nature and origin of the microheterogeneity was investigated by using electrophoretic techniques. Treatments of factor B with neuraminidase and glycopeptidase F show that this microheterogeneity is mainly due to differences in its sialic acid content, varying from seven to eleven residues per molecule, and resulting in different oligosaccharide structures. However, deglycosylated factor B reveals a residual, nonallotypic variation in the Bb region of the polypeptide backbone. We confirm the presence of four asparagine-linked oligosaccharide chains of the complex type in native factor B, two of which are located in the Ba fragment, and the two others in the Bb fragment. The prevalent isoform of the native protein carries two sialic acid residues per oligosaccharide chain. Biosynthesis experiments show that the microheterogeneity of secreted factor B from HepG2 cells is acquired during the processing of its glycans. However, in vitro-secreted factor B is more heterogeneous than the serum protein. We propose a structural model for the microheterogeneity of the native protein and its physiological fragments. We discuss as well the feasibility of electrophoretic techniques to deal with microheterogeneity analysis.

Two-dimensional gel electrophoresis of proteins

The high-resolution capacity of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) makes it an excellent tool for the analysis and characterisation of complex protein mixtures. The evolution of two-dimensional electrophoresis is briefly described. The various steps involved in 2-D PAGE, the identification and characterization of proteins separated by 2-D PAGE and the quantitative and qualitative analysis of 2-D patterns are discussed in detail and some new approaches are described. In the final section a brief outline of some of the biomedical applications of 2-D PAGE to screening of body fluids, genetic diseases, inborn errors of metabolism, cancer and neoplastic transformation are discussed.

Inulin-induced activation of factor B in whole serum: description of structural modifications in the Ba fragment

The investigation of inulin-induced conversion of human factor B in serum by isoelectrofocusing revealed physiological modifications in the primary structure of the Ba fragment. Evidence has been obtained that a nascent Ba, generated by the hydrolytic action of the D component on B in serum, was a short-lived product and that a fast release of carboxy-terminal arginine and lysine residues occurred involving a serum carboxypeptidase B enzyme.

Cobra venom acetylcholinesterase: nature of charge isoforms

Charge isoforms of cobra (Naja naja oxiana) venom acetylcholinesterase, separated by isoelectric focusing, differ only by the number of free carboxyl groups of glutamic and/or aspartic acid side-chains in the enzyme molecule. The isoforms appear to be produced by a post-translational deamidation of accessible glutamin and/or asparagine residues. The isoforms have identical catalytic specificities towards characteristic acetylcholinesterase substrates.

New developments in isoelectric focusing

Recent developments of isoelectric focusing (IEF) are summarized. New approaches to the synthesis of carrier ampholytes are described and some controversial aspects of their properties, especially in regard to their molecular weight, are critically discussed. New aspects of preparative techniques, such as "steady-state rheoelectrolysis" and continuous-flow recycling IEF, are presented. New methodological trends of analytical IEF, such as agarose, cellulose acetate, ultrathin-layer and sub-zero temperature IEF are discussed. Among analytical applications, particular emphasis has been placed on detection of neutral mutations, IEF of peptides, IEF of cells and organelles and on titration curves. The review ends with a tiny chapter on a vast field, the explosive field of two-dimensional techniques.

Electrophoretic separation of A gamma and G gamma human globin chains in Nonidet P-40

Electrophoresis in cellulose acetate in the presence of 3% Nonidet P-40 can resolve two neutral genetic variants, A gamma and G gamma human fetal globin chains. The ratio of these two chains, determined by densitometry of the electrophoretic strips, is in excellent agreement with the Gly-Ala ratio obtained by chemical analysis of the cyanogen bromide fragment gamma CB3. It is suggested that the detergent binds preferentially to the hydrophobic amino acid segment 133-141 in the A gamma chain, thus masking either a Lys or an Arg residue at the two extremes.