Antigenic analysis of purified surface antigens of filarial nematode Setaria digitata.

The surface antigens of S. digitata were isolated by treatment with Triton X-100. In non SDS-PAGE the surface antigen preparation resolved into more than 6 protein bands. Electroelution of gel slices corresponding to the protein bands with relative mobilities 0.09, 0.32, 0.41, 0.53, 0.61 and 0.76 gave 6 purified surface antigen fractions (SAF). Analysis of SAFs by SDS-PAGE showed that the proteins with molecular weights 17, 29 and 36 KD were the three major polypeptides and different combination of these gave rise to the 6 native surface proteins. The 29 KD protein existed as a monomer and as cross-linked with the 17 and 36 KD proteins. All surface antigen fractions showed antigenicity, where as 29 KD protein remained as a high avidity surface antigen.     

Identification of surface antigens of Sarcocystis muris (Coccidia)

Zoites of Sarcocystis muris were recovered from the skeletal muscles of infected mice by trypsin digestion. Extracts of zoites prepared by freeze-thaw, Triton X-100 (0.1%), or a combination of the two treatments contained antigenic components. Testing of these antigens by agar gel diffusion and immunoelectrophoresis against sera from infected mice showed one major precipitin band. SDS-polyacrylamide-gel electrophoresis (SDS-PAGE) of the extracts revealed at least eight detectable polypeptides ranging in molecular weight from 10,000 to 220,000. The antigenic components of the extract were identified by labeling the parasite surface with [125I] and precipitation of the [125I]-labeled antigens with immune sera. Analysis of the immunoprecipitates by SDS-PAGE and autoradiography revealed three antigens with molecular weights of 27,500, 43,000 and 90,000. The smallest of these was the predominant antigen as suggested by labeling intensity.     

EVIDENCE FOR A COMMON EVOLUTIONARY ORIGIN OF LIGHT-HARVESTING FUCOXANTHIN CHLOROPHYLL a/c-PROTEIN COMPLEXES OF PAVLOVA GYRANS (PRYMNESIOPHYCEAE) AND PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE)1

A fucoxanthin-chlorophyll a/c-protein complex has been isolated from the prymnesiophyte Pavlova gyrans. Thylakoid membranes were treated with the mild anionic detergent sodium taurodeoxycholate followed by sucrose density gradient centrifugation. The brown fraction produced by this procedure was treated with Triton X-100 followed by a second sucrose density gradient centrifugation. A brown fraction isolated from this gradient was shown to be a light-harvesting complex nearly identical to that which is present in the diatom Phaeodactylum tricornutum. The complexes from the two organisms have nearly identical absorption and flourescence spectra, both complexes contain fucoxanthin and two other carotenoids, both contain four polypeptides of similar molecular weights, and polypeptides from both complexes cross react with antibodies raised to polypeptides of the Phaeodactylum tricornutum complex. Results suggest a common evolutionary origin for these light-harvesting complexes, in apparent contrast to the great differences in cell structure between prymnesiophytes and diatoms.     

Identification of Surface Antigens of Sarcocystis muris (Coccidia)

Zoites of Sarcocystis muris were recovered from the skeletal muscles of infected mice by trypsin digestion. Extracts of zoites prepared by freeze-thaw, Triton X-100 (0.1%), or a combination of the two treatments contained antigenic components. Testing of these antigens by agar gel diffusion and immunoelectrophoresis against sera from infected mice showed one major precipitin band. SDS-polyacrylamide-gel electrophoresis (SDS-PAGE) of the extracts revealed at least eight detectable polypeptides ranging in molecular weight from 10,000 to 220,000. The antigenic components of the extract were identified by labeling the parasite surface with [¹²⁵I] and precipitation of the [¹²⁵I]-labeled antigens with immune sera. Analysis of the immunoprecipitates by SDS-PAGE and autoradiography revealed three antigens with molecular weights of 27,500, 43,000 and 90,000. The smallest of these was the predominant antigen as suggested by labeling intensity.     

Disruption of the quaternary structure of (Na+ + K+)-dependent adenosine triphosphatase by Triton X-100.

(Na⁺ + K⁺)-dependent adenosine triphosphatase (NaK ATPase) consists of two polypeptide chains, a large polypeptide with a molecular weight of about 100,000, and a sialoglycoprotein with a molecular weight of about 40,000. In the presence of Triton X-100 both polypeptides react to form high molecular weight aggregates with apparent molecular weights of 168,000, 200,000 and 260,000. These aggregates arise as a result of disulfide bond formation which results from the autooxidation of sulfhydryl groups on the two polypeptides of NaK ATPase. These data are discussed in light of studies aimed at determining the size and subunit structure of membrane proteins with Triton X-100.     

The detergent solubility properties of a malarial (Plasmodium knowlesi) variant antigen expressed on the surface of infected erythrocytes

Four detergents have been compared for identification of the Plasmodium knowlesi variant antigen on infected erythrocytes by immunoprecipitation analysis. Erythrocytes infected with late trophozoite and schizont forms of cloned asexual parasites were labeled by lactoperoxidase-catalyzed radioiodination and extracted either with the anionic detergents sodium dodecyl sulfate (SDS) or cholate, the neutral detergent Triton X-100, or the zwitterion 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS). After addition of Triton X-100 to SDS and cholate extracts, parallel immunoprecipitations of the four extracts were performed using rhesus monkey antisera of defined agglutinability. Identical results were obtained with clone Pk1(A+), which has 125I-variant antigens of Mr 210,000 and 190,000, and with clone Pk1(B+)1+, which has variant antigens of Mr 200,000-205,000. SDS yielded maximal levels of immunoprecipitated 125I-variant antigens. Variant-specific immunoprecipitation was detected in some experiments with Triton X-100 and cholic acid but with significantly lower recovery than with SDS. CHAPS extraction did not yield the variant antigens on immunoprecipitation. The variant antigens could also be identified in Triton X-100-insoluble material by subsequent extraction with SDS, indicating that failure to recover these proteins in the Triton X-100-soluble fraction is due to failure of this detergent to extract the variant antigens rather than to degradation during extraction. We suggest that the 125I-variant antigens either have a structure that renders them intrinsically insoluble in Triton X-100, cholate, or CHAPS, or that they are associated in some way with host cell membrane components that also resist solubilization by these detergents.     

Immunoelectrophoretic analysis of erythrocytic stages of Plasmodium yoelii and P. chabaudi

Triton X-100 extracts of erythrocytes infected with Plasmodium chabaudi and P. yoelii were analysed in crossed immunoelectrophoresis with rabbit antisera. The parasite origin of the antigens detected was assessed by metabolic radiolabelling of the parasites with 35S-methionine. About 12 immunoprecipitates were obtained with both extracts and their homologous antiserum. Cross-tests showed that the two parasite strains were very similar antigenically. Species-specific antigens could, however, also be demonstrated. Two antigens, present on both P. yoelii- and P. chabaudi-infected erythrocytes, were located on the surface of the host cell membrane as judged from 125I-labellings with lactoperoxidase. Experiments with phenyl-Sepharose showed that most of the antigens detected were hydrophilic and none of them reacted with concanavalin A.     

Polypeptides of the Epstein-Barr virus membrane antigen complex.

Epstein-Barr virus (EBV)-associated membrane antigens have been purified from the plasma membranes of the producer cell line P3HR-1 NONO. The antigens were assayed with a specific rabbit anti-ebv antiserum using an 125I-labeled staphylococcal protein A binding assay. The antigens have been shown to be present on purified plasma membranes. Treatment of the plasma membranes with Triton X-100 allows the separation of two antigenically distinct classes of antigens, one soluble and one insoluble in the detergent. Immunoprecipitates of [125I5- and [35S]methionine-labeled, detergent-soluble antigens contained three major polypeptides of molecular weights of 350,000, 140,000, and 75,003 (on 7.5% sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and several minor components. These polypeptides were all specifically precipitated from four EBV-producer cell lines, P3HR-1, P3HR-1 NONO, B95-8, and 7744. They could not be precipitated from producer cell lines treated with phosphonoacetic acid, which inhibits late viral functions, nor could they be precipitated from nonproducer cell lines. The 350,000 and 75,000 molecular weight polypeptides bound to Ricin and lentil lectin columns; however, most of the 140,000 molecular weight material did not. A component of molecular weight 220,000 (prominent only in P3HR-1 NONO) was probably a degradation product of the 350,000 molecular weight polypeptide.     

Identification of the protein producing transmembrane diffusion pores in the outer membrane of Pseudomonas aeruginosa PA01.

The outer membrane of Pseudomonas aeruginosa PA01 is permeable to saccharides of molecular weights lower than about 6000. Triton X-100/EDTA-soluble outer membrane proteins were fractionated by ion-exchange chromatography in the presence of Triton X-100 and EDTA, and the protein contents of the various fractions analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Each of the major protein bands present in the Triton X-100/EDTA soluble outer membrane was separated from one another. Adjacent fractions were pooled, concentrated and extensively dialyzed to reduce the Triton X-100 concentration. Vesicles were reconstituted from lipopolysaccharide, phospholipids and each of these dialyzed fractions, and examined for their ability to retain [14C]sucrose. Control experiments indicated that the residual levels of Triton X-100 remaining in the dialyzed fractions had no effect on the formation or permeability to saccharides of the reconstituted vesicles. It was concluded that a major outer membrane polypeptide with an apparent weight of 35,000 is a porin, responsible for the size-dependent permeability of the outer membrane.     

Identification of the protein producing transmembrane diffusion pores in the outer membrane of Pseudomonas aeruginosa PA01

The outer membrane of Pseudomonas aeruginosa PA01 is permeable to saccharides of molecular weights lower than about 6000. Triton X-100/EDTA-soluble outer membrane proteins were fractionated by ion-exchange chromatography in the presence of Triton X-100 and EDTA, and the protein contents of the various fractions analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Each of the major protein bands present in the Triton X-100/EDTA soluble outer membrane was separated from one another. Adjacent fractions were pooled, concentrated and extensively dialyzed to reduce the Triton X-100 concentration. Vesicles were reconstituted from lipopolysaccharide, phospholipids and each of these dialyzed fractions, and examined for their ability to retain [¹⁴C]sucrose. Control experiments indicated that the residual levels of Triton X-100 remaining in the dialyzed fractions had no effect on the formation or permeability to saccharides of the reconstituted vesicles. It was concluded that a major outer membrane polypeptide with an apparent weight of 35 000 is a porin, responsible for the size-dependent permeability of the outer membrane.     

Immunological analysis of plant mitochondrial NADH dehydrogenases.

Plant mitochondrial NADH dehydrogenases were analysed by two immunological strategies. The first exploited an antiserum raised to a preparation of SDS-solubilized mitochondrial-inner-membrane particles. By using a combination of activity-immunoprecipitation and crossed immunoelectrophoresis, it was shown that Triton X-100-solubilized membranes contain at least three immunologically distinct NADH dehydrogenases. Two of these were subsequently isolated by line immunoelectrophoresis and analysed for polypeptide composition: one contained three polypeptides with molecular masses of 75, 62 and 41 kDa; the other was a single polypeptide with a molecular mass of 53 kDa. The other approach was to probe plant mitochondrial membranes with antibodies raised to a purified preparation of ox heart rotenone-sensitive NADH dehydrogenase and subunits thereof. Cross-reactions were observed with the subunit-specific antisera against the 30 and 49 kDa ox heart proteins. However, the molecular masses of the equivalent polypeptides in plant mitochondria are slightly lower, at 27 and 46 kDa respectively.     

Crossed immunoelectrophoretic studies of the solubility immunogenicity of herpes simplex virus antigens.

The nonionic detergent Triton X-100 was capable of solubilizing 90% of the protein content in herpes simplex virus (HSV)-infected rabbit cornea cells. The solubilized HSV antigens formed well-characterized precipitates by crossed immunoelectrophoresis in Triton X-100-containing agarose gel, allowing both identification and relative quantitation. Water-soluble and detergent-requiring HSV antigens were identified by different solubilization procedures in buffer with and without detergent. Five glycoprotein antigens were solubilized only in the presence of detergent, indicating their membrane-bound state. One non-glycosylated antigen was present in both a water-soluble and a membrane-bound form. Based upon the crossed immunoelectrophoretic precipitating patterns of Triton X-100-solubilized HSV antigens, it has been estimated that infected cells yield an amount of virus-specific protein equivalent to 2,000 enveloped virions per cell. Rabbits inoculated intracutaneously with Triton X-100-solubilized HSV antigens developed neutralizing antibodies against HSV almost as effectively as rabbits with an active HSV infection. Precipitins against individual HSV antigens in sera from rabbits infected with HSV and immunized with the Triton X-100-solubilized HSV antigens were assayed by the crossed immunoelectrophoretic technique. Sera from infected rabbits reacted more strongly and with a higher number of HSV antigens than sera from immunized rabbits.     

Purification and Characterization of Neutral and Acid Sphingomyelinases from Rat Brain

Neutral and acid sphingomyelinases were copurified from a rat brain P2 fraction by extraction with 1% Triton X-100, followed by (NH4)2SO4 fractionation, acetone powdering, extraction with 1% Triton X-100, (NH4)2SO4 fractionation, Sepharose CL-6B chromatography, and chromatofocusing. The neutral sphingomyelinase was eluted with buffer containing 0.4 M NaCl after the acid sphingomyelinase had been eluted with Polybuffer at pH 5.3. The neutral sphingomyelinase exhibited specific activity of 48,300 nmol/h/mg of protein, with 254-fold purification; the corresponding value for acid sphingomyelinase was 25,300 nmol/h/mg protein, with 668-fold purification from the P2 fraction. The purified neutral sphingomyelinase had no acid sphingomyelinase activity, and vice versa. The properties of the two enzymes were examined. A single band corresponding to a molecular weight of 67,000 was obtained on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for both enzymes. The pI was estimated to be 5.5 for both on isoelectric focusing. The native molecular weights of the neutral and acid sphingomyelinases were found to be 434,000 and 284,000, respectively, on gel filtration with Sepharose CL-6B. The single band obtained for each enzyme on SDS-PAGE was identified as an antigen with antibody raised against the purified neutral sphingomyelinase. Their amino acid compositions were very similar. The neutral and acid sphingomyelinases probably consist of common polypeptides and are immunologically cross-reactive.     

Protein composition of the chromosomal scaffold and interphase nuclear matrix

Residual protein structures were prepared from isolated chromosomes and interphase nuclei of in vitro cultured bovine liver cells and the protein compositions were analysed. Chromosomes with minimal cytoplasmic contamination were obtained by a simple procedure using a pH 8 isolation medium containing Triton X-100 and polyamines, and residual protein-DNA complexes were prepared by extraction with 2 M NaCl. Residual protein structures were also obtained by digesting isolated chromosomes with staphylococcal nuclease. Protein compositions of both structures as obtained by SDS-polyacrylamide gel electrophoresis were essentially the same. Residual protein structures were prepared from isolated nuclei by the same procedures. The major nuclear matrix proteins, i.e., the lamins A, B, and C, were not found in the chromosomes and chromosome scaffolds. On the other hand, the residual chromosome structures contained two major polypeptides of 37 and 83 kilodalton relative molecular weights that were absent from the nuclear matrix preparations. A few polypeptides with the same or very similar electrophoretic mobilities were found in the residual structures of both the nuclei and the chromosomes.     

Characterization of two antigenically related integral membrane proteins of the guinea pig sperm periacrosomal plasma membrane

The periacrosomal plasma membrane of mammalian spermatozoa functions both in recognition and in binding of the egg's zona pellucida and in the acrosome reaction. This study characterizes two antigenically related proteins with molecular weights of 35 kD (PM35) and 52 kD (PM52) of the guinea pig sperm periacrosomal plasma membrane. Polyclonal antisera were prepared against electrophoretically purified PM35 or PM52. Each antiserum recognized both the 35-kD and 52-kD polypeptides on Western blots, indicating that they are structurally related. This conclusion was supported by peptide mapping experiments demonstrating comparably sized fragments of both PM35 and PM52. Both PM35 and PM52 behave as integral membrane proteins during phase-separation analysis with Triton X-114. Electron microscopic immunocytochemistry and differential fractionation of sperm membranes established that both PM35 and PM52 are exclusively localized to the periacrosomal plasma membrane. Three different antisera were used for ultrastructural studies, and each specifically bound the cytoplasmic but not the extracellular membrane surface. The electrophoretic mobilities of the PM35 and PM52 polypeptides were unchanged during sperm maturation and during the ionophore-induced acrosome reaction. The localization of PM35 and PM52 suggests a potential role for these integral plasma membrane proteins in signal transduction or membrane fusion events of the acrosome reaction. © 1994 Wiley-Liss, Inc.     

Isolation and immunochemical characterization of fractions from membranes of Aspergillus fumigatus with protease activity

Two fractions exhibiting acid protease activity (AFPI and AFPII) were isolated by extraction of membrane vesicles of Aspergillus fumigatus with Triton X-100. These two fractions produced single bands in both polyacrylamide and sodium dodecyl sulfate polyacrylamide gel electrophoresis and showed apparent molecular weights of 73,000 and 43,000, respectively. Molecular weights determined by gel filtration in the absence and presence of Triton X-100 and sedimentation velocities in analytical ultracentrifugation indicated hydrophobic characteristics, since both fractions readily aggregated and complexed with Triton X-100; both exhibited elevated enzyme activities in the presence of Triton X-100. Carbohydrate content was 93% for AFPI and 85% for AFPII. The enzymatic fractions demonstrated different pH optima in the acid range as well as different temperature stabilities. Both protease fractions cross reacted in double immunodiffusion, while in crossed immunoelectrophoresis both demonstrated five precipitin peaks, each with similar patterns. AFPI demonstrated two additional precipitin peaks in crossed immunoelectrophoresis. As determined by crossed immunoaffinoelectrophoresis, the protease fractions demonstrated galactose and mannose residues. In biotin-avidin enzyme-linked immunosorbent assay both fractions reacted with allergic bronchopulmonary aspergillosis and aspergilloma sera. It can be concluded that two fractions with protease activity of A. fumigatus reported here may be of significance in Aspergillus-induced diseases.     

Structural proteins of two salmonid rhabdoviruses.

Purified infectious hematopoietic necrosis (IHN) virus and the virus of haemorrhagic septicaemia (VHS) (Egtved virus) each contain five structural proteins which were designated L, G, N, M-1, and M-2. The IHN viral polypeptides have molecular weights estimated to be 157,000, 72,000, 40,000, 25,000 and 20,000, respectively, whereas those of VHS viral polypeptides are estimated to be 157,000 74,000, 41,000, 21,500, and 19,000, respectively. The carbohydrate composition of the glycoprotein (G) was confirmed by demonstrating selective incorporation of [3H]glucosamine into the designated G protein of both viruses. Phosphoproteins were identified by incorporation of [32P]orthophosphate into the N and M-1 proteins of IHN virus and into the N protein of VHS virus. The glycoprotein of each virus was selectively solubilized by treatment with Triton X-100 in low salt buffer, whereas the M-1, and M-2 proteins along with the G protein were solubilized by Ttition X-100 in 0.43 M NaCl. The protein composition of the salmonid rhabdoviruses resembles that of the rabies virus group more closely than the vesicular stomatitis virus group.     

Characterisation of the cell envelope of Treponema hyodysenteriae

Abstract Cell envelope preparations of Treponema hyodysenteriae (strain CN 8368) were examined using biochemical and immunochemical methods. Several major polypeptides were detected with molecular weight between 24-kDa and 45-kDa. The majority of these polypeptides were recognised by serum from a pig vaccinated with an experimental whole-cell T. hyodysenteriae vaccine and hyperimmune anti- T. hyodysenteriae rabbit sera. Immune electron microscopy confirmed that the major antigens detected were associated with the cell envelope. Triton X-100, in the presence of EDTA, completely solubilised a polypeptide with an approximate molecular weight of 36-kDa. Antibodies to this polypeptide were not absorbed by whole T. innocens cells.     

Immunochemical Analysis of Triton X-100-Insoluble Residues from Micrococcus lysodeikticus Membranes

Triton X-100-insoluble residues from Micrococcus lysodeikticus membranes were analyzed by crossed immunoelectrophoresis after dispersal of the residues in sodium dodecyl sulfate (SDS). Conditions which produce no obvious distortion of the immunoprecipitate profile and which allow qualitative and quantitative analyses of the antigens present in the extracts are described. Two main antigens were detected; these were identified as succinate dehydrogenase (EC 1.3.99.1) and adenosine triphosphatase (EC 3.6.1.3). As determined by peak area estimations, the maximal release of succinate dehydrogenase and of adenosine triphosphatase from Triton X-100-insoluble membrane residues occurred at protein/SDS ratios of about 4.3:1 (0.2% SDS) and 6.8:1 (0.13% SDS), respectively. A comparison of enzyme activities of SDS extracts with those of untreated, control Triton X-100-insoluble membrane residues indicated that both the succinate dehydrogenase and the adenosine triphosphatase antigens were released with a full (or enhanced) catalytic potential at or below concentrations of SDS required to effect maximal solubilization of the enzyme in question. Evidence is also presented to suggest that the more acidic of the two components detected by crossed immunoelectrophoresis for the heterogeneous adenosine triphosphatase antigen is more sensitive to SDS than is the other. Both succinate dehydrogenase and adenosine triphosphatase lost catalytic activity and were denatured at protein/SDS ratios lower than 3.4:1.     

Biochemical and immunological characterization of the microfibrillar ecto-endoplasmic boundary in the ciliate Isotricha prostoma

The cytoplasm of the ciliated protozoan Isotricha prostoma is compartmented by a continuous fibrillar system made up of a double layer of 4 nm-diameter filaments: the microfibrillar ecto-endoplasmic boundary (EEB). Isolation of this structure after treatment of the cells in a buffer of low ionic strength in the presence of the detergent Triton X-100 evidenced connections linking the two filamentous layers. One dimensional electrophoresis on SDS-polyacrylamide gel of EEB fractions revealed several major proteins with apparent molecular weights between 11 and 23 K. Of these, two neighboring bands of MW22 and 23 K were removed from gels and used as antigens to obtain rabbit antibodies. The antiserum obtained reacted specifically with injected proteins as shown by the technique of immunological detection on nitrocellulose sheets using the peroxidase reaction product. Electron microscopy localization of the antigens with anti-IgG coupled with colloidal gold showed significant labeling of the EEB within the cortex of Isotricha permeabilized with Triton X-100. We hope that the 22-23 K antiserum will prove to be a useful tool for the comparative study of other non-actin filament systems in Protozoa.