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At least 523 records · Page 29Linked to original sources
PubMed1994

Dot blot analysis of rat gastric mucin using histochemical staining methods.

Rat gastric mucins blotted on various membranes were detected using the periodate-Schiff staining method. The use of a polyvinylidene difluoride (PVDF) membrane gave the best results compared to nitrocellulose, nylon, positively charged nylon, and positively charged PVDF membranes. Alcian blue, high-iron diamine, galactose oxidase-cold thionin Schiff, and paradoxical concanavalin A stainings were also performed to detect mucins on PVDF membranes. Mucins were quantitatively detected by this analysis using each staining method with a range of detection from 0.02 to 1 microgram. Mucins extracted from rat gastric mucosa were detected by these dot blot assays at the position of void volume during Sepharose CL-4B chromatography. Mucins, after being purified with cesium trifluoroacetate centrifugation, were also mainly excluded from a Sepharose CL-2B column and detected by the dot blot assay using each staining method. In contrast, mucins after reduced alkylation were separated into two fractions during Sepharose CL-2B chromatography; one was excluded but the other was included in the column. Both fractions were detected using the periodate-Schiff method, but only the excluded fraction was stained using the paradoxical concanavalin A staining method. Thus, the dot blot assay using histochemical staining methods is useful for detecting individual mucins during gel chromatography.

Animals↗
PubMed1995

Detection of glycoprotein receptors on blotting membranes by binding of live bacteria and amplification by growth.

Conditions have been adapted for detecting bacteria bound to glycoprotein receptors on blotting membranes using a self-enhancing detection method based on bacterial growth. Neutrophil plasma membrane proteins, mediating adherence of mannose-binding type-1-fimbriated Escherichia coli and concanavalin A (Con A) to intact human neutrophils, were separated by SDS-PAGE and transferred onto a polyvinylidene difluoride (PVDF) membrane. The PVDF membrane was immersed in a suspension of mannose-binding type-1-fimbriated E. coli, and after repeated washings, bound bacteria were allowed to multiply into bacterial colonies by placing the membrane on a solid nutrient substratum. About one major and eight minor glycoproteins, some of which also were detected by Con A, selectively induced colony formation in a mannose-inhibitable fashion. Binding of [35S]methionine metabolically labeled E. coli to PVDF membranes produced a virtually identical binding pattern, demonstrating further the accuracy of this self-enhancing detection method which is rapid, simple, and sensitive and avoids radioisotopes.

Bacterial Adhesion↗
PubMed1995

An improved assay method for the measurement and detection of sphingomyelinase activity.

We have developed an improved assay method to measure sphingomyelinase activity and to detect this enzyme separated on polyacrylamide gels. The assay of sphingomyelinase activity involved immobilizing [N-methyl-14C]sphingomyelin on polyvinyldiflouride (PVDF) membrane, incubation with sphingomyelinase, and the measurement of radioactivity associated with [14C]phosphocholine. The enzyme activity was dependent on the concentration of sphingomyelin, enzyme, pH, and temperature. Thirty minutes of incubation time was optimal for enzyme activity. This enzyme had a bimodal pH optima, in that optimum enzyme activity was measured at pH 5.4 and 7.4. The detection of sphingomyelinase was pursued by separating the enzyme on a polyacrylamide gel and carrying out the enzyme assay by exposure to [14C]sphingomyelin blotted on a PVDF membrane. The enzyme activity on the PVDF membrane was visualized by autoradiography. A white band (depicting hydrolytic removal of [14C]sphingomyelin from PVDF was observed. Our method of detecting sphingomyelinase by immobilizing sphingomyelin on PVDF membrane may serve as a prototype for assaying various other enzymes in which the hydrolytic product is released into the aqueous phase. Moreover, our method for detecting sphingomyelinase on polyacrylamide gels may be helpful in further studies on the molecular biochemistry of this and related phospholipases.

Acrylic Resins↗
PubMed1995

Direct mass spectrometric analysis of glycosphingolipid transferred to a polyvinylidene difluoride membrane by thin-layer chromatography blotting.

A simple, rapid method for the analysis of glycosphingolipid that combines "thin-layer chromatography (TLC) blotting" and mass spectrometry is reported. Glycosphingolipids developed by TLC were transferred to a polyvinylidene difluoride membrane by TLC blotting, after which the glycosphingolipid band on the membrane was excised and placed on a mass spectrometer probe tip, and a few microliters of triethanolamine was added as the matrix. The sample was analyzed by secondary ion mass spectrometry. About 1 microgram of glycosphingolipid subjected to TLC can be analyzed. The major advantage of this method is that glycosphingolipid can be analyzed structurally without purification by repeated column chromatography.

Animals↗
PubMed1995

A method for monitoring the glycosylation of recombinant glycoproteins from conditioned medium, using fluorophore-assisted carbohydrate electrophoresis.

We have developed a method for monitoring the N-glycosylation of recombinant glycoproteins directly from conditioned medium samples. Proteins in the conditioned medium are separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electroblotted onto polyvinylidene fluoride membranes. After staining the membranes with Coomassie blue, the protein(s) of interest is excised. Oligosaccharides are released from the membrane-bound glycoprotein by digesting with peptide N4-(acetyl-beta-glucosaminyl) asparagine amidase and labeled with the fluorophore 8-aminonaphthalene-1,3,6-trisulfonate (ANTS). Labeled oligosaccharides are then separated on polyacrylamide gels which allow for the direct comparison of samples. We have shown that recombinant human lysosomal hydrolase alpha-galactosidase A is N-glycosylated with both sialylated and phosphorylated oligosaccharides. ANTS-labeled oligosaccharide bands from alpha-galactosidase A were isolated from polyacrylamide gels. Sialylated and phosphorylated bands were identified by shifts in their electrophoretic mobility after digesting with neuraminidase or alkaline phosphatase to remove sialic acid or phosphate groups, respectively. Using the ANTS-labeled oligosaccharides from alpha-galactosidase A, we have shown that polyacrylamide gels can be used to resolve sialylated and phosphorylated oligosaccharide structures.

Amidohydrolases↗
PubMed1995

Rapid immunodetection on polyvinylidene fluoride membrane blots without blocking.

The data presented here (Fig. 2, Table 2) clearly demonstrate that wetting of Immobilon-P is not required for immunodetection of transferrin. It can be inferred that the immobilized transferrin undergoes sufficient rehydration at the molecular level to permit epitope recognition by the antibodies, even when the surrounding areas of PVDF remain hydrophobic. The hydrophobic blot procedure was compatible with blots prepared by both tank and semidry transfer and with the substrates BCIP/NBT and 4CN. Additionally, the binding specificity of antitransferrin antiserum was not altered in the hydrophobic blot protocol. Given the diversity of blocking agents, antibodies, and visualization systems available, optimization for specific reagent combinations may be necessary. The most important parameters will be the concentration of blocking agents and detergents used since either, depending on chemical properties and concentration, may cause the membrane to wet out during incubation. This procedure is not applicable to nitrocellulose membranes since surfactants are used in their manufacture specifically to cause wetting in aqueous buffers.

Animals↗
PubMed1995

New methods using polyvinylidene difluoride membranes to detect enzymes involved in glycosphingolipid metabolism.

Two new methods are described using polyvinylidene difluoride (PVDF) membranes to detect enzymes involved in glycosphingolipid metabolism. One is the detection of enzymes on a PVDF membrane to which glycosphingolipids have been transferred from an HPTLC-plate by TLC blotting. The glycosphingolipids on the membrane were incubated with an enzyme preparation, and the resulting product was detected by immunostaining with a monoclonal antibody directed to the product. IV(3)NeuAc(alpha)Lc(4)Cer that had been transferred to a PVDF membrane was incubated with Clostridium perfringens sialidase. Lc(3)Cer then was transferred to the membrane, and the whole incubated with bovine milk beta1-4 galactosyltransferase, after which the product, nLc(4)Cer, was detected by immunostaining with the monoclonal antibody H11 that recognizes the GAl(beta)1-4GlcNAc(beta)1-3Gal structure of neolactoseries glycosphingolipids. This method detects glycosphingolipid-metabolizing enzymes that produce the same epitope. The second method is the detection of enzymes located on a polyacrylamide gel. A sialidase preparation from C. perfringens was subjected to native polyacrylamide electrophoresis then transferred to a PVDF membrane impregnated with IV(3)NeuAc(alpha)nLc(4)Cer as the enzyme substrate. The membrane then was incubated, and the resulting product, nLc(4)Cer, detected by immunostaining with the monoclonal antibody H11. The area stained shows the location of the sialidase on the polyacrylamide gel. The method is effective for determining the apparent molecular weight(s) of the enzyme(s) in the crude enzyme preparation. This was demonstrated by using crude sialidase preparation from C. perfringens.

Chromatography, Thin Layer↗
PubMed1996

Peptide-mass profiles of polyvinylidene difluoride-bound proteins by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in the presence of nonionic detergents.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), in conjunction with enzymatic digestion of proteins and molecular weight search of peptide-mass database is a powerful technique for peptide/protein identification. Ideally, peptide mixtures should be compatible with both MALDI-TOF and microsequencing. In our laboratory, enzymatic digestion and extraction of peptides from polyvinylidene difluoride (PVDF)-bound proteins is performed in the presence of nonionic detergents. However, nonionic detergents have been shown to cause signal suppression in MALDI-TOF analysis. This study demonstrates that by using a modified matrix solution, peptide-mass fingerprinting of PVDF-bound proteins by MALDI-TOF can be obtained in the presence of nonionic detergents such as hydrogenated Triton X-100 (RTX-100), octylglucopyranoside, and Tween 20.

Amino Acid Sequence↗
PubMed1996

A simple assay method for bacterial binding to glycosphingolipids on a polyvinylidene difluoride membrane after thin-layer chromatography blotting and in situ mass spectrometric analysis of the ligands.

A simple assay method for bacterial binding to glycosphingolipids on a polyvinylidene difluoride (PVDF) membrane has been developed. Glycosphingolipids were separated on a high-performance thin-layer chromatography (HPTLC) plate and transferred onto a PVDF membrane by TLC blotting [Taki, T., Handa, S., and Ishikawa, D. (1994) Anal. Biochem. 221, 312-316]. The PVDF membrane was blocked with phosphate-buffered saline containing 4% casein and 0.1% methionine and overlaid with 35S-labeled Escherichia coli possessing K99 fimbriae (E. coli K99) at 37 degrees C for more than 2 h. Binding of the 35S-labeled E. coli K99 was detected with a bioimaging analyzer. Radioactivities were located on the bands corresponding to N-glycolylneuraminic acid containing glycosphingolipids such as sialylparagloboside, GM2, and GM3 with hydroxy fatty acid in ceramide moiety, and a weak binding was detected on the band of N-acetylneuraminylparagloboside. Furthermore, an in situ mass spectrometric analysis of the ligand glycosphingolipids on the membrane was demonstrated. The present method has several advantages compared with the overlay binding assay on the HPTLC plate as follows: (i) the method is simple and rapid; (ii) the membrane is easy to handle; (iii) binding is clear with low background; (iv) a small amount of [35S]methionine is required; and (v) sensitive ligand characterization can be done by in situ mass spectrometric analysis.

Bacterial Adhesion↗
PubMed1996

Methodical analysis of protein-nitrocellulose interactions to design a refined digestion protocol.

We have analyzed the efficacies of seven different organic solvents, 13 organic bases, and 17 detergents to dissociate electroblotted proteins from nitrocellulose. Most efficient were a 1% piperidine-40% acetonitrile mixture and 1% concentrations of either cetyltrimethylammonium bromide or several polyoxyethylene and zwitterionic detergents at pH > or = 8.5. In general, detergent-promoted elution varied with pH (8.5-->12.0) and temperature (37-->65 degrees C) in a detergent-dependent and protein-dependent manner, making for unpredictable results of any combination. However, Zwittergent 3-16, as the major exception, eluted proteins of different sizes and properties almost equally well at pH 8.5. This preferred effect is not enhanced by addition of organic solvent. In fact, detergent/acetonitrile mixtures were generally less efficient for protein elution. Zwittergent 3-16 (1% in 100 mM NH4HCO3) proved to be the most powerful additive for one-step enzymatic digestion of nitrocellulose-bound proteins, both in terms of highest recoveries (including endoproteinase Lys-C digestions) and general applicability, a major improvement over the use of Tween 80 and hydrogenated Triton X-100. The new digest procedure takes just 2 h to complete and requires 5 ng protease per 1 microliter buffer per 1 mm2 of nitrocellulose; relatively large pieces of membrane (> or = 100 mm2) can be successfully processed. The same detergent is a satisfactory additive for digestion of polyvinylidene difluoridebound proteins as well. Moreover, Zwittergent 3-16 is fully compatible with the usual downstream procedures. It is uv (OD214) transparent and does not interfere with high-performance liquid chromatography in any other way. Apparent incompatibility with direct (i.e., "prechromatography") matrix-assisted laser-desorption ionization time-of-flight mass spectrometry can be either reduced by methanol washing of the dried sample and activation of a low-mass gate or eliminated by a simple microliter cleanup procedure.

Chromatography, High Pressure Liquid↗
PubMed1996

Discrimination between acid and alkali-labile phosphorylated residues on Immobilon: phosphorylation studies of nucleoside diphosphate kinase.

We have critically analyzed current methodologies for distinguishing histidine and serine phosphorylated residues in proteins and report a simple technique that assures a reliable discrimination. Electro-transfer of a phosphorylated enzyme to Immobilon membranes and its treatment at pH 1 and 14 in buffers containing 5% methanol allows unambiguous distinction between serine/threonine and histidine phosphorylation (O-phosphomonoesters and phosphoramide, respectively) since under these conditions only one type of residue is dephosphorylated. The addition of 5% methanol to all buffers was indispensable to deplete phosphate from membranes incubated successively under acid and basic conditions. The technique was applied to the study of nucleoside diphosphate kinase (NDP kinase) phosphorylation. In this enzyme, autophosphorylation of active site histidine is an accepted intermediate step in the catalytic phosphate transfer activity of nucleoside diphosphate kinase (NDP kinase). Nonetheless, a significant degree of autophosphorylation on other residues has been reported by several laboratories, and the hypothesis has been advanced that this nonhistidine phosphorylation may play an important role in NDP kinase cellular function, signaling the suppression of metastasis in the case of human NDP kinase A. Using this improved method, we show that human, Escherichia coli and Candida albicans NDP kinases are only autophosphorylated on histidine residues. In addition, we present evidence that the presence of phosphoserine after strong acid hydrolysis of the histidine autophosphorylated enzyme is in fact a nonenzymatic transphosphorylation from phosphohistidine due to the harsh acid treatment. This methodology was also applied to in vivo phosphorylation studies of C. albicans NDP kinase. We believe that the technique will be generally useful in histidine phosphorylation screenings.

Candida albicans↗
PubMed1997

TLC blotting: application to microscale analysis of lipids and as a new approach to lipid-protein interaction.

A simple method for the transfer of phospholipids and glycosphingolipids from a high-performance thin-layer chromatography (HPTLC) plate to a polyvinylidene difluoride (PVDF) membrane, called thin-layer chromatography (TLC) blotting, and its application in lipid research are described. Most of the lipids developed on the HPTLC plate are blotted quantitatively. Detection of the lipids on the membrane is done by chemical and immunological staining. This method makes it possible to purify individual lipid components separated on an HPTLC plate and to determine the structures of lipids in limited biological samples when combined with direct mass spectrometric analysis (TLC blotting/MS). A binding assay and the identification of ligands for microorganisms can be made using TLC blotting/MS. In addition, simple methods for the detection of enzymes on a substrate-immobilized PVDF membrane are described.

Animals↗
PubMed1997

Semidry electroblotting of peptides and proteins from acid-urea polyacrylamide gels.

A semidry electrophoretic transfer method was developed for efficient electroblotting of proteins separated by acid-urea polyacrylamide gel electrophoresis (AU-PAGE). Model polypeptides ranging from 1.8 to 21.5 kDa were used to test transfer parameters that included time of transfer, power settings, transfer solutions, and membrane type. Optimized conditions were identified which allowed for transfer efficiencies of 70-100% following 5-15 min of applied current. The best transfer solution was 5% acetic acid, the same solvent used for electrophoresis. Therefore, acid-urea gels could be subjected to electrophoretic transfer without a soaking step, thereby reducing loss of band resolution and eliminating leaching of protein from the gel. The method was shown to be applicable to Western blot analysis of rat neutrophil defensins.

Acetic Acid↗