Mapping of seminal plasma proteins by two-dimensional gel electrophoresis in men with normal and impaired spermatogenesis

The present study analyses differential polypeptide expression of seminal plasma from fertile and infertile men by two-dimensional gel electrophoresis. Optimization of solubilization of seminal plasma was obtained by using [3-(3-(cholamidopropyl) dimethyl-ammonio)-1-propane sulphonate] and chaotropic agent mixture in lysis buffer before separation in immobilized pH gradient for isoelectric focusing. A two-dimensional map of seminal plasma from a fertile man allowed the detection of about 750 spots. Semi-preparative electrofocusing was performed. Analysis of tryptic fragments of two major spots by matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectroscopy resulted in identification of prostatic acid phosphatase and prostate specific antigen. Three groups of spots and seven individual spots of isoelectric point from 4.6 to 6.2 and mol. wt from 41 to 18 kDa disappeared in the two-dimensional maps of seminal plasma of vasectomized men (n = 4) and of a patient with bilateral anorchidy as compared to that of fertile men (n = 5). Some of these polypeptides were also absent in seminal plasma of patients with alterations of seminiferous tubules showing Sertoli cell-only syndrome characteristics (n = 4) and could be potential diagnostic markers of spermatogenesis impairment.

Two-dimensional polyacrylamide gel electrophoresis of the protease SP220K, a renal cell carcinoma marker

The present study analyses, by two-dimensional polyacrylamide gel electrophoresis, the protease SP220K isolated from renal cell carcinoma. The pure molecule is separated using either immobilized pH gradient or isoelectric focusing in conventional carrier ampholyte in the first dimension. Some interactions with the acrylamide matrix in isoelectric focusing are discussed. The results demonstrate that two-dimensional gel electrophoresis performed with enriched media such as basolateral membranes, allows the detection of the protease. In addition, the non detection of the molecule up to now by this methodology can be explained by the high tendency of oligomerization of SP220K. Effectively the high molecular weight form of the molecule of 220 kDa is favoured in two-dimensional gel electrophoresis over monomeric forms which are better detected in SDS PAGE. This was confirmed by immunostaining performed with an antiserum to SP220K produced by nitrocellulose-bound antigen.

Resolution of high molecular weight proteins in dependence on electric field strength in polyacrylamide gel electrophoresis

Resolution of high molecular weight proteins, in the upper region of polyacrylamide gels, was studied in relation to the type of electric field. Separations by constant field gel electrophoresis (CFGE) were compared to those in pulsed oscillatory high-performance electrophoresis (POPE), a novel technique which allows electrophoresis at high field strengths owing to a novel local field distribution. This distribution contributes to structural and mechanical stability of the gel with resultant well-reproducible separation, enhanced resolution, and higher absolute mobility of proteins in POPE.

Pulsed field electrophoresis for the separation of protein-sodium dodecyl sulfate-complexes in polyacrylamide gels

Polyacrylamide gel electrophoresis of proteins was studied using a pulsed-current mode. A new "local field" distribution was used to correct the gel patterns and optimize migration. A corrective field was applied at fixed 2 s intervals to a constant field, inducing a complex relaxation mechanism. Calculated variations in the local field directions decreased the electric strain on the gel during the run, with resultant optimum gel structure. The relaxation mechanism was found to enhance the absolute mobility of proteins with shorter running times compared to constant field gel electrophoresis (CFGE) and other pulsed field techniques. The enhancement of molecular mobility was explored by transverse pore gradient gel electrophoresis. Ferguson curves which exhibited a convex shape in CFGE were linearized by the new pulsed-field method named pulsed oscillatory high-performance electrophoresis (POPE).

Lane distortions in gel electrophoresis patterns

Distortions effects were studied as a function of gel environment, apparatus design and buffer type. Outward lanes distortions pronounced in low conductivity buffers for both continuous buffer systems and stacking gels, were field strength dependent. In discontinuous buffer systems, the moving boundary of the Laemmli buffer system deformed depending on the environment. In the Michov buffer system, the high conductivity resolving gel surrounded by a low conductivity electrode buffer, displayed straight pathways until a field strength of 15 V/cm, permitting to obtain information about lanes distortions depending on the acrylamide matrix structure. A decreased ammonium persulfate concentration, e.g. to 0.03%, induced phase segregation in gels at low temperature during the run: a critical endpoint near 11 degrees C for a gel in the Michov buffer system under conditions of electrophoresis was supposed. Gel collapse resulted in inward deviations in the lanes of the pattern and also faint bands in the zones where the gel was retracted. Besides this effect of catalyst concentration, the inwardly distorted pattern depended on temperature, field strength, solvent and hydrolysis due to gel aging. Amendments for overcoming lane distortions are suggested.

Fast electrotransfer of human serum proteins in their native state from polyacrylamide thin gradient gels reinforced by textiles to polyvinylidene difluoride membranes. Rapid electrotransfer from thin gradient gels reinforced by textiles

A fast electroblotting technique of native molecules electrophoretically separated in thin (0.25 to 0.5 mm) gradient gels, onto a high capacity membrane of polyvinylidene difluoride is described. Omitting methanol during transfer, the equilibration step is avoided and the same buffer is used in electrophoresis and transfer. As the gel reinforced by fabric never swells nor shrinks, and as all the bands are blotted, the transfer matrix exactly reflects the protein pattern of the original gel. Autoradiography is enhanced and electroelution is homogeneous in all parts of the gels. Significant improvement is noticed in binding proteins of molecular weight from about 20 kDa to more than 700 kDa, as suggested by complete electroelution of all native serum components.

Improved transfer of high molecular weight proteins using fabric-reinforced soft polyacrylamide gels

Rapid transfer of electrophoretically separated, high molecular weight proteins from fabric-reinforced, soft, low-concentration polyacrylamide gels (3.5%T, 2.6%C) is described. Polyester fabrics proved useful for gel reinforcement during vertical slab gel electrophoresis. The fabric-reinforced gel retains its dimension during transfer, equilibration and drying, facilitating comparison of protein bands in the separation gel and transfer matrix.

Use of mild detergent gel electrophoresis for isolation and characterization of the kidney brush border D-glucose transporter

Gradient gel electrophoresis was performed under mild detergent conditions to separate pig kidney brush border membrane proteins and to identify the smallest functional molecular protein entity of the D-glucose transporter. The various protein bands obtained from the nondenaturing gel system in a semipreparative scale were eluted by electrodialysis. These proteins were then reintegrated into proteoliposomes and tested for D-glucose-inhibitable [3H]phlorizin binding. The D-glucose transporter had a molecular mass of 70 kDa in mild detergent electrophoresis conditions and in subsequent SDS analysis.

Separation and reconstitution of sodium-dependent glucose transport activity from renal brush-border membranes using gel-filtration chromatography

Pig kidney brush-border membrane vesicles were solubilized using a final concentration of 1% Triton X-100, found optimal for quantitative reconstitution of D-glucose transport into liposomes. Using reconstituted proteoliposomes, selective permeability towards D-glucose compared to other sugars tested was shown as well as the main features of D-glucose transport in native membranes, namely sodium dependence and phlorizin inhibition of D-glucose accumulation. After removal of Triton X-100 from the detergent extract, some membrane proteins (about 40%), which are insoluble in the absence of detergent, were isolated. Among these proteins resolubilized by 1% Triton X-100, the component catalyzing the D-glucose transport was located by gel-filtration chromatography separation, using reconstitution of transport as the assay. The active fraction displayed a molecular size of 50 A; when analyzed on SDS polyacrylamide gel electrophoresis, it contained one major protein subunit with an apparent molecular weight close to 65,000. We conclude that this protein fraction is involved in D-glucose transport by renal brush borders.

Influence of sodium ions on detergent solubilization of pig brush border D-glucose transport system for reconstitution experiments

The D-glucose uptake by liposomes resulting from the association of egg lecithins with solubilized membrane proteins was measured in order to assess their sodium dependent D-glucose transport activity. Membrane proteins were extracted by Triton X-100 solubilization of pig kidney brush border membrane vesicles, which were suspended either in KCl medium or in NaCl medium. When measured by equilibrium isotope exchange procedure in sodium conditions, the D-glucose uptake by sodium detergent extract associated to liposomes occurred with a higher velocity than that obtained with liposomes reconstituted from potassium detergent extract. No differences were observed in the permeability or in the protein content of two types of liposomes. These results are discussed in terms of activation of D-glucose transport system induced by sodium ions before membrane protein solubilization.

Crossed-immunoelectrophoretic study on human renal brush border membrane vesicles

The human kidney brush border membrane proteins were studied by crossed-immunoelectrophoresis. An antiserum against membrane vesicles was raised in rabbits and used in establishing a reference immunoelectrophoregram with the antigens released by Triton X-100. Among the precipitates observed, the following hydrolases were identified by zymogram staining: Microvillus aminopeptidase (EC 3..4.11.2), gamma-glutamyltransferase (EC 2.3.2.2), maltase (EC3.2.1.20) and trehalase (EC 3.2.1.28). Depletion of the antiserum with sealed, right-side-out vesicles was performed. No precipitates could be seen when the Triton X-100 extract was electrophoresed in a gel containing the depleted antibody. It is therefore suggested that the precipitation of membrane components by the complete antibody is mainly due to externally-located determinants and that the precipitates of the reference pattern correspond to membrane components pointing, at least in part, towards the tubular lumen. Evidence was also noted for a differential removal of antibodies directed against the different antigens. Such an observation could not be explained by the antigen accessibility nor by its amount in the membrane. Parallel crossed-immunoelectrophoresis of Triton X-100 and papain extracts gave rise to an "identity" pattern for only some antigens, particularly for microvillus aminopeptidase and maltase. It is thus strongly suggested that the papain-released form of these enzymes bears nearly all the antigenicity of the whole molecule.

Effect of massive proximal small bowel resection on intestinal brush border membrane proteins in the dog

Dog enterocyte brush border proteins have been studied after a 75% proximal resection of the small bowel. This study was carried on microvillar membrane preparations purified from ileal mucosa sampled before and after regeneration on neighbouring intestinal segments, each animal acting as its own control. After six weeks of regeneration a statistically significant decrease of the following enzyme specific activities was observed: lactase, cellobiase, maltase, sucrase, palatinase, dextranase, trehalase, alkaline phosphatase, aminopeptidase and gamma-glutamyl transferase. Analysis of brush border proteins by polyacrylamide gel electrophoresis in presence of sodium dodecyl sulphate have shown after regeneration a decreased rate for the proteins with a molecular weight higher than 100,000 daltons. Modifications of electrophoretic patterns seem to be related to the specific activity decreases observed for brush border enzymes after regeneration, since the molecular weight of these enzymes were found between 116,000 and 285,000 daltons, after gel filtration.

[Microvilli membrane proteins from dog enterocytes]

Mcrovilli membranes have been isolated from dog jejunal and ileal enterocytes. Proteins were analysed by polyacrylamide gel electrophoresis after solubilization with sodium dodecylsulphate. The recovery of the membrane fraction with this purification method was found to be 22% and the specific activity of sucrase increases 19 folds in the membrane fraction. Microvilli membrane proteins after polyacrylamide gel electrophoresis were seprated in 21 bands, most of them with a molecular weight higher than 70 000. Seven bands with molecular weight from 150 000 to more than 340 000, were found to be glycoproteins.

Occurrence of slowly sedimenting components with mu chain antigenicity in normal adult and cord serum

The occurrence of trace amounts of slowly sedimenting components with mu chain antigenicity was investigated in 8 normal adult sera and 4 sera from cord blood of new-born infants. Separation of these components from 19S IgM was obtained by density gradient ultracentrifugation. The fractions were studied by radioimmunoassay. The results suggest that slowly sedimenting components with mu chain antigenicity occur in normal adult serum in amounts located in the mug/ml range. Several components sedimenting with various speeds were identified, although their sedimentation coefficients were not measured. This fact suggests that not only the already described 7S IgM monomer exists in normal blood but that other modes of association between mu and L chains or mu chains fragments also occur. Sera from cord blood showed patterns similar to that of adults.