Visualization of lactoperoxidase binding to microtubule and tubulin

The binding of lactoperoxidase to microtubules and tubulin was shown in both electron micrography and polyacrylamide gel electrophoresis by tracing the enzymatic activity of lactoperoxidase. Lactoperoxidase bound to purified microtubules appeared to distribute evenly on the surface without forming special structures. Both alpha and beta-tubulin separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis bound lactoperoxidase, and could be detected by the use of lactoperoxidase reaction. Electrophoretic study revealed that the interaction between lactoperoxidase and tubulin were not strictly specific and a variety of proteins other than alpha- and beta-tubulin, including actin and neurofilament subunits, bound lactoperoxidase.     

The estimation and comparison of molecular weight of angiotensin I converting enzyme by sodium dodecyl sulfate-polyacrylamide gel eletrophoresis.

The angiotensin I converting enzyme from rat lung was observed to be a glycoprotein containing 8.3% carbohydrate and consisting of a single polypeptide chain with an estimated molecular weight of 139 000 as determined by sodium dodecylsulfate-polyacrylamide gel electrophoresis and 150 000 by sucrose density gradient sedimentation analysis. A comparison of the mobility of angiotensin I converting enzyme from rat lung, rabbit lung, and two hog lung sources on sodium dodecyl sulfate-polyacrylamide gels indicates that all four enzymes have very similar molecular weights and subunit structures. Some previously reported molecular weight discrepancies appear to be due to anomalous behavior of the enzyme of gel filtration.     

Structural heterogeneity of the lipopolysaccharides of the Neisseriaceae

Lipopolysaccharides from 5 different genera of the Neisseriaceae were analyzed on sodium dodecylsulfate-polyacrylamide gel electrophoresis, and visualized by silver staining. Significant heterogeneity in the banding patterns was observed with some of the strains producing only low molecular mass molecules and others producing O-repeating units. All genera examined except Branhamella contained strains that were able to produce an O-repeating side chain on their lipopolysaccharides. The ability to produce the repeating subunit did not correlate with the presence of plasmids.     

One-step isolation of alpha 1-acid glycoprotein.

alpha 1-Acid glycoprotein could be isolated by a one-step extraction method from human sera and plasma. Protein recovered in the water phase after extraction with phenol at 70 degrees C for 20 min was verified as human alpha 1-acid glycoprotein when it was compared with the reference standard human alpha 1-acid glycoprotein by Ouchterlony double immunodiffusion, sodium dodecylsulfate-polyacrylamide gel electrophoresis, Western blot analysis, and periodic acid-Schiff stain. The present isolation procedure is simple and fast, and can extract about 81% of the total alpha 1-acid glycoprotein in the sera and plasma, as determined by radial immunodiffusion.     

Disappearance of a basic chromosomal protein from cells of a mouse temperature-sensitive mutant defective in histone phosphorylation

The amount of a basic nuclear protein which migrates a little slower than histone H1 in urea-acetic acid-polyacrylamide gel electrophoresis and a little faster than H1 in sodium dodecylsulfate-polyacrylamide gel electrophoresis, decreases when cells of a temperature-sensitive mutant, ts85, derived from a mouse carcinoma cell line, are incubated at the nonpermissive temperature (39°C). This protein appears again, when cells cultured at 39°C are shifted down to the permissive temperature, indifferent to the added cycloheximide. Neither in wild type nor in a revertant of ts85, the protein disappeared at 39°C. Since the ts85 cells were found to be defective in chromosome condensation and in the phosphorylation of histone H1 at 39°C (1,2), this basic protein may relate to the both events.     

The association on SDS-polyacrylamide gels of lipopolysaccharide and outer membrane proteins of Pseudomonas aeruginosa as revealed by monoclonal antibodies and Western blotting

Abstract Monoclonal antibodies raised against single serotype components of a Pseudomonas aeruginosa vaccine have been shown to bind to the O antigen region of lipopolysaccharide (LPS). Outer membrane (OM) proteins, prepared by detergent treatment of envelope fractions and by EDTA/sonication treatment of whole cells, were separated on sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE), electrophoretically transferred to nitrocellulose membrane and reacted with LPS-specific monoclonal antibodies. The patterns produced revealed that many of the protein bands were in fact protein-LPS complexes.     

Properties of the cell envelope and a cell-envelope protein of Pseudomonas facilis

The molecular weight of the protein moiety of a phospholipoprotein complex isolated from Pseudomonas facilis has been examined with a variety of sodium dodecylsulfate-polyacrylamide gel electrophoretic systems. A molecular weight of 35 000 was determined for the protein in all analyses. A 35 000-dalton protein was present in the EDTA extract of P. facilis and in the cytoplasmic and outer membrane fractions, but not in the lipopolysaccharide and peptidoglycan. Prior inoculation of mice with the phospholipoprotein complex led to a 7.5- to 15-fold increase in the LD₅₀ when mice were subsequently inoculated with Salmonella typhimurium; this pathogen has a cell-surface protein which cross-reacts immunologically with antibody to the P. facilis phospholipoprotein complex.Abbreviations KDO 2-keto-3-deoxyoctanoate - LD₅₀ the dosage of Salmonella typhimurium at which there is 50% survival in mice - LPS lipopolysaccharide - PLP phospholipoprotein - P_PLP the protein moiety of PLP - SDS sodium dodecylsulfate - SDS-PAGE sodium dodecylsulfate-polyacrylamide gel electrophoresis - TMS trimethylsilyl     

Specific binding of tubulin to a guanine nucleotide-binding inhibitory regulatory protein in adenylate cyclase system, Ni

A protein was isolated from the soluble fraction of rat brain by affinity chromatography with Sepharose to which guanine nucleotide-binding inhibitory regulatory protein in adenylate cyclase system, Ni, was immobilized. The molecular weight of this protein, specifically bound to the Ni-affinity column, was estimated as 54,000 on sodium dodecylsulfate-polyacrylamide gel electrophoresis. Alternately prepared tubulin also bound to the Ni-affinity column. The amino acid compositions of these proteins were also identical. It is strongly suggested that this Ni-binding cytosolic protein is tubulin.     

Analysis of electrophoretically heterogeneous lipopolysaccharides of Escherichia coli by immunoblotting

Abstract The purified lipopolysaccharide (LPS) from each of four Escherichia coli serogroups which was separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and visualized by periodic acid-silver staining, exhibited a different distribution of bands. The same serogroup-specific banding patterns were evident on immunoblots developed with homologous but not heterologous O-antisera. Thus, the electrophoretic heterogeneity of LPS was confirmed and the multiple bands seen on SDS-PAGE further shown to contain O-serogroup-specific antigenic determinants.     

Purification and Chemical Characterization of a W2 Protein from Brain Myelin

Abstract: Starting from a pellet of beef brain myelin insoluble in chloroform/ methanol (2:1, vol/vol) (Wolfgram protein fraction), a pure W2 protein with apparent molecular weight of 52,000 was isolated by a simple preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis method. A comparative chemical analysis was carried out between purified W2 and a standard tubulin. Glutamic acid and arginine were the N-terminals detected. Similar peptide maps and amino acid composition were also found in both proteins. Immunological cross-reactivity was detected when W2 protein was tested against antitubulin serum. These results suggest that W2 protein could have a tubulin-like protein nature that is associated with the myelin membrane and could play a role in the myelination process.     

Studies on the regulation of 1-aminocyclopropane-1-carboxylate synthase in tomato using monoclonal antibodies

A partially purified preparation of 1-aminocyclopropane-1-carboxylate (ACC) synthase (EC 4.4.1.14) from tomato (Lycopersicon esculentum (Mill.) fruit tissue was used to generate monoclonal antibodies (MAb) specific for the two different MAbs yielded a 50-kDa polypeptide as shown by sodium dodecylsulfate-polyacrylamide gel electrophoresis. An enzyme-linked immunosorbent assay (ELISA) capable of detecting <1 ng of antigen was developed. The ELISA system was used to demonstrate that two of the MAbs recognized different epitopes on the ACC-synthase protein. Wound-induced increases in ACC-synthase activity in tomato fruit tissue were correlated with changes in ELISA-detectable protein. In-vivo labeling of wounded tissue with [³⁵S]methionine followed by extraction and immunopurification in the presence of various protease inhibitors yielded one major radioactive band of 50 kDa molecular mass. Pulse labeling with [³⁵S]methionine at various times after wounding indicated that the wound-induced increase in ACC-synthase activity involved de-novo synthesis of a rapidly turning over 50-kDa polypeptide.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - ELISA enzyme-linked immunosorbent assay - MAb monoclonal antibody - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis     

Plasmic degradation of bovine fibrinogen and non-crosslinked fibrins in solution and in gel form.

1. Analysis of degradation processes of bovine fibrinogen by bovine plasmin using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a study on the mode of changes of the properties related to clotting of digestion products as a function of time were performed. Gross features and patterns very similar to those which had been reported with human fibrinogen-plasmin systems were obtained. 2. Based on the molecular size of the degradation products and the mode of appearance and disappearance of the degradation products, the processes could tentatively be divided into three stages: stage 1, where fibrinogen (mol. wt 370 000) was degraded to produce fragments X1 (330 000) and X2 (290 000); stage 2, fragment X2 was degraded with appearance of Y (210 000) and D1 (140 000); stage 3, appearance of fragments D1, D2 (110 000), and D3 (100 000) sequentially and E (68 000) with concomitant disappearance of Y. 3. A microseparation method, which is a combination of dansylation and sodium dodecylsulfate-polyacrylamide gel electrophoresis, was devised to analyze the events of stage 1 in detail, and a molecular model for the process was proposed. 4. The plasmic degradation processes of bovine non-cross-linked fibrins in solution and in gel form were compared with that of fibrinogen and it was found that the state of the substrates, fibrins, could cause differences in the degradation patterns. With the former substrate, essentially the same sodium dodecyl sulfate-polyacrylamide gel electrophoretic patterns as those with fibrinogen were obtained. With the latter substrate, however, a distinct difference in the mode of degradation of beta chains was observed.     

Calcium-activated neutral protease inhibitor from rabbit erythrocytes lacks the N-terminal region of the liver inhibitor but retains three inhibitory units

Endogenous inhibitors for calcium-activated neutral protease (CANP) were purified from rabbit erythrocytes and liver. The purified inhibitors showed single bands but with significantly different mobilities on sodium dodecylsulfate-polyacrylamide gel electrophoresis. Peptide mapping and sequencing analyses have revealed that the erythrocyte inhibitor (429 residues) retains the C-terminal three repetitive units of the liver inhibitor (639 residues), which contains four potential repetitive units for inhibition of CANP. The erythrocyte and liver inhibitors inhibited 3 and 4 moles of CANP on the basis of the molecular weights of 46,000 and 68,000, respectively.     

Comparative partial purification of the active dicarboxylate transport system of rat liver, kidney and heart mitochondria

Hydroxylapatite chromatography of Triton-extracted inner-membrane proteins from rat liver mitochondria allowed a ten-fold purification of the dicarboxylate carrier. The purified system, reconstituted into liposomes, displayed all the properties of the dicarboxylate carrier and mediated malonate-malate and malonate-phosphate exchanges. Six protein bands of Mr ranging from 27,000 to 34,000 could be resolved by sodium dodecylsulfate-polyacrylamide gel electrophoresis. The purification of the dicarboxylate carriers of liver, kidney and heart mitochondria were carried out by this method and their properties were compared with respect to transport activity and electrophoresis patterns. Our results demonstrate that the dicarboxylate carrier of rat mitochondria can be obtained in an advanced state of purification and with a high specific activity.     

Comparison of selected analytical techniques for protein sizing, quantitation and molecular weight determination

Protein analysis techniques are developing fast due to the growing number of proteins obtained by recombinant DNA techniques. In the present paper we compare selected techniques, which are used for protein sizing, quantitation and molecular weight determination: sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE), lab-on-a-chip or microfluidics technology (LoaC), size exclusion chromatography (SEC) and mass spectrometry (MS). We compare advantages and limitations of each technique in respect to different application areas, analysis time, protein sizing and quantitation performance.     

Production of Serine Proteases by the Oyster Pathogen Perkinsus marinus (Apicomplexa) In Vitro

ABSTRACT. Analysis of the cell-free supernatants of Perkinsus marinus cultures by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and silver staining revealed the presence of as many as 17 bands ranging in molecular weight from 239 to 32 kDa. These bands were not present in un-inoculated medium. Moreover, P. marinus produces extracellular proteins that possess proteolytic activities; the cell-free supernatants of P. marinus cultures could digest a variety of proteins including gelatin, casein, fibronectin and laminin. Oyster plasma was also digested by cell-free culture supernatants. The proteolytic activity in cell-free culture supernatants was detected 24 h post-inoculation, while no proteolytic activity could be detected in cell lysates. The proteolytic activities were characterized using substrate-impregnated sodium dodecylsulfate-polyacrylamide gels and had approximate molecular weights ranging from 55 to 35 kDa. The proteolytic activity of cell-free culture supernatants was inhibited by the serine protease inhibitors phenylmethylsulphonyl fluoride, 3,4-dichloroisocoumarin and soybean trypsin inhibitor. In contrast, inhibitors (i.e. trans-epoxysuccinyll-leucylamido(4-guanidino)-butane, 1, 10-phenanthroline, captopril, ethylenediaminetetracetic acid, pepstatin A or diazoacetyl-DL-norleucine methyl ester) from the other three classes of proteases had no effect. It was concluded that the P. marinus proteases in cell-free culture supernatants are serine proteases.     

Studies on prephenoloxidase-activating enzyme from cuticle of the silkworm Bombyx mori. II. Purification and characterization of the enzyme

Prephenoloxidase-activating enzyme has been purified approximately 4800-fold from cuticular extract of the silkworm, and the preparation seems to be homogeneous as judged by disc- and dodecylsulfate-polyacrylamide gel electrophoresis. By means of gel filtration through Sephadex G-100, it has been supposed that the enzyme exists as mono- and dimeric forms at slightly acidic pH, while a monomeric form is predominant under slightly alkaline condition. The molecular weight of the monomer was estimated to be 33,000–35,000 by dodecylsulfate-polyacrylamide gel electrophoresis and gel filtration.It has been demonstrated that ester substrates for trypsin, benzoyl-l-arginine ethyl ester and tosyl-l-arginine methyl ester, can be hydrolyzed by the purified enzyme. Several lines of evidence indicating that a single protein is involved in both activation and esterolytic reactions have been presented. Some enzymatic properties of the purified preparation as esterase have also been described.In connection to esterase activity of the purified enzyme, a mechanism of prephenoloxidase activation in the silkworm system has briefly been discussed.     

The plant aminoacyl-tRNA synthetases. Purification and characterization of valyl-tRNA, tryptophanyl-tRNA and seryl-tRNA synthetases from yellow-lupin seeds.

Valyl-tRNA, tryptophanyl-tRNA, and seryl-tRNA synthetases from yellow lupin seeds Lupinus luteus were purified to homogeneity by ammonium sulfate fractionation, hydrophobic chromatography on aminohexyl-Sepharose column and affinity chromatography on tRNA-Sepharose column. Valyl-tRNA synthetase consists of one polypeptide chain of molecular weight 125000 as judged by Sephadex G-200 gel filtration and dodecylsulfate-polyacrylamide gel electrophoresis in the presence of reducing agent. Seryl-tRNA synthetase, Mr equals 110000, is composed of two 55000-Mr subunits. Tryptophanyl-tRNA synthetase exhibits molecular weight of 200000 on Sephadex G-200 and 37000 in dodecylsulfate-polyacrylamide gel electrophoresis. This indicates that tryptophanyl-tRNA synthetase consists of several subunits (probably four). Since the seryl-tRNA synthetase exhibits the same mobility on dodecylsulfate-polyacrylamide gels both in the presence and absence of reducing agent it is concluded that there is no covalent bond(s) between the subunits of the enzyme. There is also no covalent bond(s) between the subunits of tryptophanyl-tRNA synthetase. Effect of anti-sulfhydryl reagents, monovalent salts, pH and different buffers on activity of the three synthetases is described. Kinetic constants for the substrates of the synthetases are also given. dATP is a substrate for seryl-tRNA synthetase but not for valyl-tRNA and tryptophanyl-tRNA synthetases.