Sialoglycoproteins with a high amount of O-glycosidically linked carbohydrate moieties stain yellow with silver in sodium dodecyl sulfate-polyacrylamide gels

The cell envelope-bound metalloprotease (camelysin) from Bacillus cereus is a possible pathogenic factor

A novel membrane proteinase of the nosocomial important bacteria species Bacillus cereus (synonyms: camelysin, CCMP) was purified up to homogeneity as was shown by mass spectrometry in its amphiphilic form. Camelysin is a neutral metalloprotease with a molecular mass of 19 kDa. Its unique N-terminus Phe-Phe-Ser-Asp-Lys-Glu-Val-Ser-Asn-Asn-Thr-Phe-Ala-Ala-Gly-Thr-Leu-Asp-Leu-Thr-Leu-Asn-Pro-Lys-Thr-Leu-Val-Asp-(Ile-Lys-Asp)- was not detected in the protein data bases during BLAST searches, but in the partially sequenced genome of Bacillus anthracis, coding for an unknown protein. Cleavage sites of the membrane proteinase for the insulin A- and B-chains were determined by mass spectrometry and N-terminal sequencing. Camelysin prefers cleavage sites in front of aliphatic and hydrophilic amino acid residues (-OH, -SO3H, amido group), avoiding bulky aromatic residues. The internally quenched fluorogenic substrates of the matrix metalloproteases 2 and 7 were cleaved with the highest efficiency at the Leu-decrease-Gly or Leu-decrease-Ala bond with the smaller residue in the P1' position. The protein specificity is broad--all various kinds of casein were cleaved as well as acid-soluble collagen, globin and ovalbumin; intact insulin was destroyed only to a low extent. Actin, collagen type I, fibrinogen, fibrin, alpha2-antiplasmin and alpha1-antitrypsin were cleaved. The protease formed SDS-stable complexes with Glu-plasminogen and antithrombin III, visible after SDS electrophoresis by gold staining and Western blot. The CCMP-plasminogen complex caused a partial activation of plasminogen to plasmin. Camelysin interacts with proteins of the blood coagulation cascade and could facilitate the penetration of fibrin clots and of the extracellular matrix during bacterial invasion.

Differential nuclear localization of the cancer/testis-associated protein, SPAN-X/CTp11, in transfected cells and in 50% of human spermatozoa

Cancer-testis antigens (CTAs) represent potential targets for cancer immunotherapy because these proteins are widely distributed in tumors but not in normal tissues, except testes. In this paper, we identify homology of the CTA CTp11 with SPAN-X (sperm protein associated with the nucleus mapped to the X chromosome). On two-dimensional Western blots of human sperm extracts, SPAN-X antibodies recognized 19 spots ranging from 20 to 23 kDa with isoelectric points from 5.0 to 5.5. Differential extraction of spermatozoa demonstrated that the SPAN-X protein is highly insoluble. Only 50% of ejaculated spermatozoa exhibited SPAN-X immunofluorescent staining. Dual localization of the sex chromosomes and the SPAN-X protein demonstrated that an equal number of X- and Y-bearing spermatozoa exhibited SPAN-X staining. In transfected mammalian CV1 cells, the SPAN-Xa and SPAN-Xb proteins were localized to the nucleus and cytoplasm, respectively, by indirect immunofluorescence. On immunoblots of CV1 cells, the SPAN-Xa protein migrated at 15-20 kDa, whereas the SPAN-Xb protein migrated at a higher molecular weight of 21-22 kDa. The SPAN-X protein was ultrastructurally associated with nuclear vacuoles and the redundant nuclear envelope. SPAN-X is the first protein specifically localized to these poorly characterized structures of the mammalian sperm nucleus and provides a unique biochemical marker for investigation of their function in spermatozoa as well as the role of SPAN-X/CTp11 in human tumors.

Identification of a 40-kDa cell surface sialoglycoprotein with the characteristics of a major influenza C virus receptor in a Madin-Darby canine kidney cell line

Infection of cells by influenza C virus is known to be initiated by virus attachment to cell surface glycoconjugates containing N-acetyl-9-O-acetylneuraminic acid. Using an in vitro virus binding assay, we have detected this carbohydrate on several glycoproteins of Madin-Darby canine kidney cells (type I), a polarized epithelial cell line permissive for infection with influenza C virus. Among these proteins, only one was found to be present to a significant extent on the cell surface. This protein, gp40, was characterized as an O-glycosylated (mucin-type) integral membrane protein of 40 kDa, which was predominantly localized on the apical plasma membrane of filter-grown cells. It is a major cell surface sialoglycoprotein in this cell line and was shown to be subject to constitutive and rapid endocytosis. Thus, this glycoprotein can mediate not only the binding of influenza C virus to the cell surface, but also its delivery to endosomes, where penetration occurs by membrane fusion. Other highly sialylated cell surface glycoproteins were also detected but did not mediate influenza C virus binding to a significant extent, indicating that only gp40 contains 9-O-acetylated sialic acids.

Identification and characterization of carboxyl ester hydrolase as a phospholipid hydrolyzing enzyme of zymogen granule membranes from rat exocrine pancreas

Salt-washed (0.6 m NaCl) zymogen granule membranes (ZGM) of rat pancreatic acinar cells were utilized to identify and characterize membrane protein(s) responsible for phospholipase and lysophospholipase activities. Five major bands were identified in salt-washed ZGM by Coomassie Brilliant Blue. A 70-kDa protein with enzymatic activity was retained in significant quantities after several washes with 0.6 M NaCl but could be displaced from ZGM by 2 m NaCl or by 100 mg/ml heparin. By contrast, GP2, an integral membrane protein, was not displaced under these conditions. These findings suggest that the enzyme is a peripheral membrane protein of ZGM. Renaturation of ZGM proteins following electrophoresis revealed that the 70-kDa protein possessed phospholipase activity. Identification of the 70-kDa protein as a membrane-associated carboxyl ester hydrolase was based upon: (a) the use of a specific polyclonal antiserum, (b) N-terminal sequence, (c) two-dimensional gel analysis, (d) enzymatic characterization, and (e) co-localization to an area of a non-reducing gel containing significant phospholipase activity. Other ZGM proteins, namely GP2 and GP3, could not be demonstrated to possess phospholipase activity under the experimental conditions employed. Our finding that carboxyl ester hydrolase from ZGM exhibits PLA1 and lysophospholipase activities represents the first identification and characterization of a protein responsible for phospholipase activity in secretory granule membranes.

Silver staining of collagen type I after sodium dodecylsulphate polyacrylamide gel electrophoresis: effect of Maillard reaction

Differences in the acidic silver staining, after sodium dodecylsulphate polyacrylamide gel electrophoresis, between the alpha 1 and alpha 2 collagen chains, as well as between rat-tail tendon and calf-skin collagen type I, were observed. The staining conditions at which the staining differences are both most expressed and reproducible were characterized. Age differences between staining of the alpha 1 CB6 fragment from young rats (2 and 12 months) and old rats (29 months) indicated that different susceptibilities of collagen species to the silver staining can be the result of different extents of some age-dependent post-translational modification, such as glycation. In vitro incubation of acid-soluble rat-tail tendon collagen with various sugars led to an increase in silver staining compared with samples incubated in the absence of sugar. This effect was inhibited by sodium cyanoborohydride, diethylenetriamine pentaacetic acid and aminoguanidine, i.e. compounds inhibiting the Maillard reaction at various stages. It can be concluded that the enhanced silver susceptibility of glycated collagen is related to advanced-phase Maillard reaction products attached to collagen.

Purification of transfer factors

Transfer factor activities have been studied in both clinical and basic science settings for several decades. Until now, highly purified transfer factors that are suitable for molecular analysis have not been available. This has impeded progress towards understanding the molecular and cellular basis of the activities of these important inducers of cell-mediated immune responses. Murine transfer factors with specificities for chicken egg albumin or horse spleen ferritin were purified to virtual homogeneity using a combination of affinity chromatography and reversed-phase and polytypic high performance liquid chromatography (hplc). Transfer factors prepared by this methodology were recovered in high yield and in biologically-active, antigen-specific forms. The purified materials were further analyzed using sodium dodecyl sulfate polyacrylamide gel electrophoresis, chromatographic methods and an in vivo assay for immunological activity. For the first time definitions for unit transfer factor activity and specific activity are introduced. The results of these experiments indicate that transfer factors are a family of highly polar, hydrophilic molecules of low molecular weight (approximately 5,000) which are produced in small quantities by lymphoid cells and which have potent biological activity. The availability of purified transfer factors should facilitate definitive studies into the nature and mechanisms of production and action of these molecules.

Protein composition of crevicular fluid before and after treatment

Crevicular fluid (CF) analysis is a potential tool for site-specific diagnosis of periodontal disease activity. In this study, CF was collected using a novel washing method from 91 sites in 18 adult periodontitis patients both before and after conventional periodontal treatment. The sites studied were classified according to their clinical status and the number of polymorphonuclear leukocytes (PMN's) in CF samples. CF proteins were analyzed from individual sites with gel electrophoresis (SDS-PAGE). Furthermore, both the cell-bound and soluble neutral proteolytic activities of the samples were determined. Albumin was the main protein both in healthy and slightly inflamed sites. The most severely inflamed sites were characterized by high levels of low molecular weight (LMW) proteins (mol. weight ca. 12,000) and strong cell-bound neutral proteolytic activity. Scaling and root planing reduced both the LMW proteins and neutral proteolytic activity markedly in pockets responding well to treatment. The levels of the LMW proteins in CF correlated with the cell-bound neutral proteolytic activity, which reflected the number of PMN's in the sample. The present results suggest that the appearance of the LMW proteins in CF is associated with the periodontal inflammatory status of the site.

Staining and quantification of proteins separated by polyacrylamide gel electrophoresis

The present review concentrates on techniques for the staining and quantification of proteins separated by polyacrylamide gel electrophoresis. Staining with organic dyes has been used for approximately thirty years; the silver staining technique was introduced in 1979. The problems of silver staining are presented separately because the mechanism of this staining is in principle different from staining with organic dyes. Less attention has been devoted to quantification of two-dimensional gels, because this autoradiography is preferred because of its high sensitivity and fewer problems with accurate quantification in contrast to silver staining.

Clinical applications of electrophoresis of human salivary proteins

Human salivary proteins have been studied by electrophoresis in denaturing and non-denaturing polyacrylamide gel electrophoresis (PAGE) as well as by isoelectric focusing (IEF) and two-dimensional procedures, and the clinical applications of this have been reviewed. Whilst non-denaturing PAGE is useful in studying polymorphisms, sodium dodecylsulphate PAGE appears to be otherwise preferable. Immobilized pH gradients containing carrier ampholytes (CAs) give better resolution than CA-based IEF and overcome the problems of cathode drift and loss of basic material. Proline-rich proteins stain poorly with conventional procedures and special techniques are necessary. In clinical studies, findings must be viewed over and above the large number of polymorphisms which occur normally. Studies relating salivary protein and peptide profiles to dental caries susceptibility are encouraging. Specific protein abnormalities have been associated with connective tissue disorders and could form the basis of new non-invasive diagnostic procedures. Protein differences associated with cystic fibrosis and diabetes mellitus, however, merit reinvestigation with the new procedures now available. Detection of HIV antigens in saliva is a new area of research. In the light of new techniques available and new information which has arisen from DNA studies, future prospects for the clinical applications of electrophoresis of saliva look good.

Purification and partial characterization of lactacin F, a bacteriocin produced by Lactobacillus acidophilus 11088

Lactacin F, a bacteriocin produced by Lactobacillus acidophilus 11088 (NCK88), was purified and characterized. Lactacin F is heat stable, proteinaceous, and inhibitory to other lactobacilli as well as Enterococcus faecalis. The bacteriocin was isolated as a floating pellet from culture supernatants brought to 35 to 40% saturation with ammonium sulfate. Native lactacin F was sized at approximately 180 kDa by gel filtration. Column fractions having lactacin F activity were examined by electron microscopy and contained micelle-like globular particles. Purification by ammonium sulfate precipitation, gel filtration, and high-performance liquid chromatography resulted in a 474-fold increase in specific activity of lactacin F. The purified bacteriocin was identified as a 2.5-kDa peptide by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The lactacin F peptide retained activity after extraction from SDS-PAGE gel slices, confirming the identity of the 2.5-kDa peptide. Variants of NCK88 that failed to exhibit lactacin F activity did not produce the 2.5-kDa band. Sequence analysis of purified lactacin F identified 25 N-terminal amino acids containing an arginine residue at the N terminus. Composition analysis indicates that lactacin F may contain as many as 56 amino acid residues.

A retinal ganglion cell neurotrophic factor purified from the superior colliculus

Dissociated neonatal rat retinal ganglion cells can be maintained by the addition of an extract from the neonatal superior colliculus. This extract can support 95% of ganglion cells over 24 h in culture; in addition it promotes the expression of neurites from these cells. This report describes the purification of a neurotrophic factor from the superior colliculus which supports the survival of 80% of retinal ganglion cells over 24 h in vitro. The purification procedure involves a combination of dye-ligand, anion-exchange, and molecular sieve chromatography. The purified neurotrophic factor has a Stokes radius of approximately 200 A using molecular sieve chromatography in the presence of a chaotropic agent. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified factor indicates that it is a glycoprotein that migrates with a molecular mass greater than 400 kDa. Further characterization of this high-molecular-mass glycoprotein by enzymatic digestion demonstrated that it is a chondroitin sulfate proteoglycan. This factor is clearly distinguishable from other neurotrophic factors that have an effect on retinal ganglion cells such as brain-derived neurotrophic factor and fibroblast growth factor. The chondroitin sulfate proteoglycan from the neonatal superior colliculus is the first proteoglycan to be identified as a neurotrophic factor.

A micromethod for the estimation of oligosaccharides containing glycosidically linked sialic acid or hexoses, or both, in glycoproteins

The peeling reaction, the process by which oligosaccharides are degraded in alkali, was used as the basis for an assay to provide structural information about glycosidically linked oligosaccharides in glycoproteins. Glycoproteins were treated with 0.05 M NaOH at 50 degrees to induce release, and subsequent degradation ("peeling"), of glycosidically linked, but not of N-glycosydically linked, oligosaccharides. Among the degradation products generated from O-linked chains were three 3-deoxy sugar acids whose formation was correlated with certain structural features of the oligosaccharides. N-Acetylneuraminic acid was released from terminal positions in the oligosaccharides, and iso- and meta-saccharinic acids were derived from the degradation of 4-O- and 3-O-substituted hexoses, respectively. All of these sugar acids were detected colorimetrically by periodate oxidation and reaction of the product with 2-thiobarbituric acid. The ability of the method to generate 3-deoxy sugar acids was tested in 8 alkali-treated glycoproteins. 3-Deoxy sugar acids were detected only in those glycoproteins whose glycosidically linked carbohydrates contained N-acetylneuraminic acid, or 3-O- or 4-O-substituted hexoses, or both. As little as 0.12 microgram of 3-deoxy sugar acid produced from 5 micrograms of human chorionic gonadotropin was sufficient for detection. This method is novel in its ability to distinguish sialylation of glycosidically linked carbohydrates. Furthermore, it combines the specificity of beta-elimination with the sensitivity of the 2-thiobarbituric acid assay in targeting degradation products of the peeling reaction as candidates for an assay method.

Comparison of polyclonal and monoclonal antibodies to Actinomyces and Arachnia species

Polyclonal (PoAbs) and monoclonal (MoAbs) antibodies were produced to Actinomyces israelii serotypes 1 and 2, to Actinomyces naeslundii, and to Arachnia propionica, and their specificities were studied by an enzyme immunoassay (EIA). All PoAbs except those to A. propionica reacted also with at least one other Actinomyces species. Only the MoAb to A. naeslundii proved to be more specific than the corresponding PoAbs. This MoAb did not crossreact with other Actinomyces or Arachnia species, nor with any other anaerobic or aerobic bacteria studied by inhibition EIA. Immunoblotting studies indicated that the antibody specific to A. naeslundii is directed against a large molecular weight antigen (greater than 150 kd), probably polysaccharide in nature. The produced PoAbs and MoAbs can be used for further analyses of the antigenic determinants of different Actinomyces and Arachnia species.