Glycopeptides from rat brain glycoproteins

The lipid-free protein residue of rat brain tissue was treated with papain to solubilize the heteropolysaccharide chains of the tissue glycoproteins. The glycopeptides were separated into non-dialyzable and dialyzable glycopeptide preparations. Each preparation was then sorted out into groups of glycopeptides by means of electrophoresis and gel filtration. The quantitatively predominant glycopeptides were the alkali-stable glycopeptides (Group A) which accounted for 64% of the glycopeptide carbohydrate recovered from rat brain. Most of the group A glycopeptides appeared in the non-dialyzable preparation. The molecular weight of the glycopeptides of Group A ranged from approximately 5200–3700. The largest glycopeptide molecule in this mixture possessed the highest electrophoretic mobility and contained one fucose, four N-acetylneuraminic acid (NANA), six N-acetylglucosamine, four galactose, and three mannose residues per molecule. The spectrum of glycopeptides isolated in this group showed a progressive decrease in NANA rsidues, NANA and galactose residues, and NANA, galactose, and N-acetylglucosamine residues which could be correlated with a progressive decline in molecular weight and electrophoretic mobility. Some of the glycopeptides in each fraction recovered from this group of glycopeptides contained sulfate ester groups.A second group of glycopeptides (Group C glycopeptides) accounted for 25% of the total glycoprotein carbohydrate recovered from rat brain. These were recoverd from the dialyzable glycopeptide preparation, and resolved into three fractions by column electrophoresis. These glycopeptides do not contain sulfate, are composed predominately of mannose and N-acetylglucosamine, and possess a molecular weight of approximately 3000.Several minor groups of glycopeptides were detected. Alkali-labile glycopeptides (Group B) appeared in the non-dialyzable glycopeptide preparation. The dialyzable glycopeptide preparation contained glycopeptides (Group E) which contained N-acetylgalactosamine and glucose. These had a molecular weight of approximately 2000. Group D glycopeptides recovered from the dialyzable glycopeptide preparation contained variable amounts of NANA, mannose, galactose, N-acetylglucosamine, and sulfate. These possessed a molecular weight of approximately 2900.     

Gel electrophoretic fractionation of RNAs by partial denaturation with methylmercuric hydroxide.

The changes in agarose gel electrophoretic velocities of several RNAs of varying molecular weight and base composition with concentration of the denaturant, methylmercuric hydroxide (MMH), have been studied. At intermediate MMH concentrations, the mobility of any one species is intermediate between the “native” (no MMH) and fully denatured (5 mm MMH) values. A + U-richer RNAs are partially denatured at lower concentrations of MMH than are G + C-richer RNAs. Electrophoresis at intermediate MMH concentrations is useful for resolving some RNA species that are not well resolved either in the absence of MMH or under fully denaturing (5 mm MMH) conditions. It is shown that it is possible to carry out MMH electrophoresis in polyacrylamide gels; this is useful for low molecular weight RNAs. An equation to correlate changes in mobility between the native and denatured states is proposed.     

Isolation and characterization of cyanogen bromide fragments and a glycopeptide from the Dolichos biflorus lectin.

The 110000 molecular weight Dolichos biflorus lectin is a glycoprotein composed of four subunits of approximately 27000 molecular weight with one methionine residue per subunit (Carter and Etzler, 1975b). Cyanogen bromide cleavage of the lectin yielded two fragments with approximate molecular weights of 15000 and 12000 as determined by electrophoresis on sodium dodecyl sulfate gels. Only the 15000 molecular weight fragment stained for carbohydrate with the periodic acid-Schiff stain. The two fragments were isolated, and their amino acid compositions were determined. The 15000 molecular weight fragment was identified as the amino terminal segment of the lectin subunits by NH2-terminal amino acid analysis. A glycopeptide with a minimum molecular weight of 1100 was isolated from the lectin by exhaustive Pronase digestion. Complete acid hydrolysis of the glycopeptide yielded aspartic acid, mannose, and N-acetylglucosamine in the ratio of 1:4-5:1-2. Partial acid hydrolysis of the glycopeptide produced a component which had an identical mobility with commercial N-acetylglucosaminylasparagine in high voltage paper electrophoresis. The data indicate that the carbohydrate unit of the lectin is bound to the amino terminal half of the subunits by a glycosylamine linkage between N-acetylglucosamine and asparagine.     

A subfraction of fragment D isolated from a plasmin hydrolysate of human fibrinogen.

Fragment D from a 4-hour plasminolysate of human fibrinogen was chromatographed on DEAE-cellulose and a nearly homogeneous subfraction obtained. It migrated as a single band in dodecylsulfate gel electrophoresis. Reduction yielded three peptide chains with approximate molecular weights of 45000, 295000 and 13000 as estimated from the electrophoretic migration rate in dodecylsulfate acrylamide gels. From these data the molecular weight of the Fragment D subfraction was calculated to be ca. 87500. The S-carboxymethylated peptide chains were separated by chromatography on DEAE-cellulose. They were correlated electrophoretically and their amino acid composition was determined. The peptide chains of molecular weight 45000 and 29500 showed a chromatographic microheterogeneity. The subfractions of these two chains, however, were not distinguished by their electrophoretic mobility in dodecylsulfate acry lamide gels and showed only insignificant differences in their amino acid composition.     

Effect of trypsin on the cell surface proteins of hepatoma tissue culture cells. Characterization of a carbohydrate-rich glycopeptide released from a calcium binding membrane glycoprotein.

Concentrations of trypsin that bring about aggregation of hepatoma tissue culture (HTC) cells also release from the cell surface an Mr = 55,000 glycopeptide fragment. This glycopeptide fragment also accumulates in the medium, including serum-free medium, as a normal consequence of membrane protein turnover. The trypsin-released glycopeptide is labeled when cells are grown in the presence of fucose or leucine before treatment of the cells with the protease. Similarly, the glycopeptide fragment can be labeled by reacting cells in situ by lactoperoxidase-catalyzed radioiodination or by tritiated borohydride reduction of cells treated first with neuraminidase and galactose oxidase. The tryptic glycopeptide fragment was purified by concanavalin A-Sepharose chromatography, and hydroxyapatite chromatography in the presence of dodecyl sulfate. The amino acid and carbohydrate composition was determined, as was the sensitivity of the purified glycopeptide to a variety of endo- and exoglycosidases. The purified glycopeptide contains an average of 17 sialic acid residues and hence, shows charge heterogeneity after electrophoresis in isoelectric focusing gels. The charge heterogeneity can be eliminated completely by treatment with neuraminidase. The glycopeptide after this treatment is homogeneous. The trypsin-sensitive membrane glycoprotein which is the source of the Mr = 55,000 glycopeptide was identified by two-dimensional gel electrophoretic analysis of labeled cells, treated or not treated with trypsin. This glycoprotein, which has an apparent molecular weight of 85,000 and forms a homodimer in the presence of calcium ions, was purified and its identity as the parent of the Mr = 55,000 glycopeptide was confirmed by showing that the same Mr = 55,000 fragment was released by trypsin from the purified glycoprotein as was released from the intact cells.     

Anomalous behavior of the major avian myeloblastosis virus glycoprotein in the presence of sodium dodecyl sulfate.

The sodium dodecyl sulfate (SDS) complex of the major glycoprotein of avian myeloblastosis virus exhibited an anomalously low free electrophoretic mobility compared with those of non-glycosylated protein standards. The apparent molecular weight of the glycoprotein calculated from the relation between log molecular weight and electrophoretic mobility depended on the acrylamide concentration and reached a lower limit of 80,000. The molecular weight was also estimated from the retardation coefficients of protein standards and the viral glycoprotein. This method yielded a molecular weight of 64,000 for the avian myeloblastosis virus glycoprotein. When gel chromatography in SDS was used to determine the apparent molecular weight of the glycoprotein from its hydrodynamic properties alone, the estimated value was 50,000. The generally assigned value of 80,000 daltons for the avian myeloblastosis virus major glycoprotein, as determined by SDS electrophoresis, may be an overestimate due to its relatively low free electrophoretic mobility and peculiar conformation in SDS.     

Protein-polysaccharides of pig laryngeal cartilage

1. Protein-polysaccharides of chondroitin 4-sulphate were extracted with neutral calcium chloride from pig laryngeal cartilage that was not completely homogenized. The protein-polysaccharides were purified by precipitation with 9-aminoacridine. On zone electrophoresis in compressed glass fibre at pH7.2 it was separated into two fractions, although two distinct zones were not obtained. These fractions, which had already been shown to differ in their antigenic determinants, also differed considerably in amino acid composition, total protein, hexose and glucosamine contents. 2. The fraction of higher mobility contained approx. 2% of protein and only traces of glucosamine. Serine and glycine accounted for over half the total amino acid residues, but aromatic, basic and sulphur-containing amino acids were not detected. The weight-average molecular weight, determined by sedimentation, was 230000. 3. Assuming that there was the same sequence of neutral sugars at the linkage points as in PP-L fraction (protein-polysaccharide light fraction), the approximate molar ratio of hexose to serine suggested that most of the serine residues were linked to chondroitin sulphate chains. Support for this was derived from the agreement between the weight-average molecular weight of the chondroitin sulphate-peptide after proteolysis, and the chain weight calculated from its serine content. The chain weight based on the serine content of the fraction of higher electrophoretic mobility was approximately similar. 4. In contrast, the fraction of lower electrophoretic mobility resembled PP-L fraction in its amino acid composition, protein and glucosamine contents. The presence of glucosamine, together with the higher hexose content, suggested that this fraction contained some keratan sulphate. 5. The relatively low molecular weight of the fraction of higher mobility enabled it to be extracted without complete disintegration of the cartilage. The unlikelihood of its being produced by autolytic enzymes is discussed.     

Analysis of the electrophoretic migration of DNA frayed wires

We analyzed the electrophoretic behaviour of the unusual multi-stranded DNA complexes, frayed wires, in polyacrylamide gels under non-denaturing conditions. Frayed wires arise from the association of several strands of a parent oligonucleotide that possesses long terminal runs of consecutive guanines. According to the structural model proposed for frayed wires, there are two distinct conformational domains, a guanine stem and single stranded arms displaced from the stem. The presence of the two domains affects the electrophoretic migration of the frayed wires, resulting in a greater retardation compared to that of double stranded DNA of the same molecular weight. The degree of retardation is determined by the relative length of the stem and the arms; the complexes with longer arms display a stronger dependence on the total molecular weight. Reptation plots (mobility x molecular weight vs. molecular weight) were used to study the electrophoretic behaviour of frayed wires that arise from the different parent oligonucleotides. The plots are unique for each type of frayed wire. The characteristic parameter, the position of the maximum of the reptation plot, depends on the type of the frayed wire as well as the total gel concentration. The plots become similar when we replot the mobility data taking into account only the single stranded arms of the frayed wires. The positions of the maximum and the overall shape are very close for the four types of frayed wires studied.     

Protective antigens of the vaccinia virus

The comparison of the polypeptide composition of 3 vaccinia virus strains, L-IVP, B-51 and CM-63, has revealed that strains L-IVP and B-51 are similar in their polypeptide composition, while in strain CM-63 capsid polypeptide with a molecular weight of 34000 daltons is absent or has altered electrophoretic mobility. As the result of the isolation of vaccinia envelopes (from strain L-IVP) and the electrophoretic separation of their polypeptides in plates with polyacrylamide gel 10 polypeptides have been obtained in 7 fractions, each containing 1 or 2 polypeptides. The immunization of rabbits with individual fractions has demonstrated that the formation of virus-neutralizing antibodies is induced mainly by 4-5 polypeptides in 3 fractions, having the highest molecular weight (54000-31000 daltons) and constituting about 19% of all proteins in the whole virion. The low-molecular envelopes polypeptides have been found to play no essential role in inducing the formation of virus-neutralizing antibodies. The highest antibody titers (1: 15625) have been detected in antisera to the preparations of whole vaccinia virus envelopes.     

Quantitative comparative analysis of complex two-dimensional electropherograms

A protocol is described to detect and assess differences between complex electrophoretic patterns. A semiautomated method is used to collect accurate absolute mobility data from many two-dimensional electropherograms and a computer algorithm has been developed which normalizes and averages these data. The program generates refined numerical maps consisting of the mean electrophoretic mobilities and corresponding confidence limits for each component protein represented in the original two-dimensional electrophoretic pattern. Tests of statistical significance of apparent differences between averaged numerical maps are carried out to evaluate electrophoretic polymorphisms between the ribosomal proteins of two different plant species. Furthermore, using a nonlinear function relating log molecular weight to mobility, precise molecular weight estimates are obtained from measurements of electrophoretic mobilities of proteins in the presence of sodium dodecyl sulfate. Several examples are presented which demonstrate application of these semiautomated analyses to quantitative comparison and interpretation of two dimensional gel electropherograms.     

Purification and partial characterization of two basic proteins from human peripheral nerve.

Two basic proteins, denoted P1 and P2 protein, were purified from human sciatic nerve. The isolation was achieved by the following steps: delipidation with chloroform/methanol mixtures, dry acetone and dry ether; acid extraction at pH 2; ion exchange chromatography on QAE-Sephadex A-25 and gel filtration on Sephadex G-100. P1, P2 proteins and the basic protein of the central nervous system have been shown to have different electrophoretic mobility, and each of the two peripheral basic proteins was shown to be homogeneous by disc electrophoresis. The molecular weight of P1 protein is around 14 100 and that of P2 protein is around 12 200, as determined by ultracentrifugal analysis. There was some difference in the amino acid composition of human P1 and P2 protein, and a marked difference between their composition and the composition of central basic protein and bovine peripheral P1 and P2 proteins which were described previously. When injected to animals, P1 protein induced only experimental allergic neuritis while P2 protein induced both mild experimental allergic neuritis and experimental allergic encephalomyelitis. Thus, the human P1 protein is similar to the bovine P1 protein and human P2 protein is similar to bovine P2 protein, concerning their electrophoretic mobilities, molecular weights and biological properties.     

Regulation of the formation of proteinases inBacillus megaterium

The exocellular proteinases of asporogenic and sporogenicBacillus megaterium KM (megaterioproteinase A and S) were found to be active enzymes of the monomer type. The electrophoretic mobility of megaterioproteinase A is higher than that of S on acrylamide gel. After mixing, the enzymes could be separated again. The molecular weight of megaterioproteinase A was found to be 20,000–23,500, that of megaterioproteinase S 16,500–20,000 daltons, according to the “molecular sieving” method. The electrophoretic mobility of both proteinases was determined at different pH and the graphically calculated isoelectric point (pI) was found to be 7.3–7.4. The pK values of the ES complex estimated by plotting the logarithm of the maximum velocity of the enzymic reaction against pH were 6.0–6.1 and 7.8–8.0 for both megaterioproteinases. The activation energy was 13,500–13,600 for both enzymes. It is concluded that the above two enzymes resemble each other in enzymic properties but differ in electrophoretic mobility and probably also in molecular weight.     

Free solution mobility of oligomeric DNA

The free solution electrophoretic mobility of a charged oligomer in an ionic solvent that approximately takes into account relaxation field effects, screening of the velocity field, and the hydrodynamic interactions resulting from motions of the charges due to an electric field is described. For double‐stranded DNA, the free solution electrophoretic mobility under ionic strengths determined by the buffer and pH conditions relevant to capillary electrophoresis increases with increasing molecular weight up to few hundred base pairs. © 1999 John Wiley & Sons, Inc. Biopoly 49: 209–214, 1999     

The putative ''link'' glycopeptide associated with mucus glycoproteins. Composition and properties of preparations from the gastrointestinal tracts of several mammals.

The existence of a discrete 'link' peptide in epithelial mucins has been debated for many years. There is evidence that at least some mucins contain a specific 'link' peptide (or glycopeptide) that enhances mucin polymerization by forming disulphide bridges to large mucin glycoprotein subunits. A major difficulty has been to know whether the reported differences in putative 'link' components represent artifacts generated by inter-laboratory differences in technical procedures used in mucin purification. The present paper outlines the results of a collaborative study involving five laboratories and 53 samples of purified gastrointestinal mucins (including salivary, gastric, small-intestinal and colonic mucins) prepared by five techniques from four different animal species. An early step in mucin purification in all cases was the addition of proteinase inhibitors. Representative mucins were analysed for their composition, electrophoretic mobility in SDS/polyacrylamide-gel electrophoresis before and after disulphide-bond reduction, and for their reactivity with monospecific antibodies developed against the 118 kDa putative 'link' glycopeptide isolated from either rat or human small-intestinal mucins. Our results indicate that, despite differences in laboratory techniques, preparative procedures, organs and species, each of the purified mucins contained a 'link' component that was released by disulphide-bond reduction and produced a band on SDS/polyacrylamide-gel electrophoresis at a position of approx. 118 kDa. After electroelution and analyses, the 118 kDa bands from the different mucins were found to have similar amino acid profiles and to contain carbohydrate. It would appear therefore that a 'link' glycopeptide of molecular mass approx. 118 kDa is common to all of the gastrointestinal mucins studied.     

Purification and characterization of proteins,including procollagen type III,in salt extracts of fetal bovine skin

The nature of high-molecular-weight proteins in salt extracts of fetal bovine skin was investigated. A series of DEAE cellulose ion-exchange columns separated the mature collagen from the high molecular weight proteins and also separated the high molecular weight proteins from each other. The following proteins were isolated: (a) a very high molecular weight protein which appears to be aggregated mature collagen; (b) two high molecular weight proteins of slightly faster mobility on SDS polyacrylamide gels, one of which is collagen-like and one of which is not; and (c) a type III procollagen, purer than those previously reported in the literature. These latter three proteins were characterized by amino acid analysis, SDS polyacrylamide gel electrophoretic mobility, collagenase sensitivity, and CNBr peptide patterns from SDS-PAGE.     

Isolation and some properties of potato 0-diphenol oxidase]

Potato tuber o-diphenoloxidase is found to exist in heterogenous mixture of forms differing from each other in their molecular weight, electrophoretic mobility, substrate specificity. A method is proposed which permits to isolate several molecular forms of the enzyme in a relatively homogenous state. Conditions are studied, in which interconversion of o-diphenoloxidase molecular forms takes place.     

Purification and properties of the phenprocoumon-induced decarboxyfactor X from bovine plasma. A comparison to normal factor X.

1. By a procedure involving adsorption to barium sulfate, chromatography on DEAE-Sephadex and QAE-Sephadex and preparative polyacrylamide gel electrophoresis, decarboxyfactor X was purified from plasma of phenprocoumon-treated cows. No contaminants could be detected in the final preparation by polyacrylamide gel electrophoresis and zone-electrophoresis. 2. The molecular weight of decarboxyfactor X, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis is approximately 55 000, which is equal to that of factor X. The protein consists of two polypeptide chains with molecular weights of 44 000 and 17 000. 3. Decarboxyfactor X has antigenic determinants in common with normal factor X. 4. The amino acid composition and aminoterminal amino acids of normal factor X and decarboxyfactor X are identical. 5. Less than one residue of gamma-carboxyglutamate could be detected per mole of decarboxyfactor X. 6. In the absence of Ca2+, normal factor X has a slightly higher electrophoretic mobility than decarboxyfactor X. In the presence of Ca2+ the mobility of factor X decreases considerably while the mobility of decarboxyfactor X remains unaltered.     

Isolation and partial characterization of a tubulin-like protein from human and swine synaptosomal membranes.

Synaptic membranes from human and swine brains were solubilized with 8 M urea and the proteins were reduced and alkylated. A protein was isolated from both sources and had identical amino acid compositions and molecular weights as determined by electrophoresis on polyacrylamide-sodium dodecylsulfate gels and by ion-exchange chromatography and gel filtration on Bioglas 1000. The apparent molecular weight of the protein was 53 000 on the acrylamide-sodium dodecylsulfate gels. Neither neutral sugars nor sialic acid was a significant component of the protein. When the proteins were digested with trypsin and the resultant peptides subjected to chromatography (n-butanol/acetic acid/water) and electrophoresis (pH 3.7) the peptide maps were identical. The protein comprises 1-2 percent of the total synaptosomal protein. With regard to amino acid composition, molecular weight, peptide map characteristics, behavior on DEAE-cellulose columns, electrophoretic mobility and sugar content, the synaptic protein is quite similar to the monomer of swine tubulin.     

Purification and physico-chemical characteristics of chorionic alpha1-microglobulin

Highly purified chorionic alpha-microglobulin was isolated from amniotic fluid by precipitation with lantham chloride, ammonium and lithium sulfates coupled with adsorption chromatography with calcium pyrophosphate. The following physicochemical properties of the protein were determined: molecular weight, relative electrophoretic mobility, interaction with protamine sulfate and lectins, enzymatic stability and precipitation with salts.     

Characterization of protamines from four avian species

No data are available on the protamines of birds, with the exception of galline. We have characterized the protamines from four species of birds belonging to four different orders. All of them have very similar properties. They have been purified by carboxymethylcellulose chromatography and analyzed with respect to amino acid composition and electrophoretic behaviour. They are very arginine-rich proteins (63.4-67.3%) but do not contain lysine. Serine (12.0-18.2%), tyrosine (5.8-9.0%) and glycine (4.5-7.1%), along with arginine, make up the bulk of the amino acid residues in these molecules. The electrophoretic mobility of bird protamines in acetic acid-urea-polyacrylamide gels is intermediate between that of somatic histones and salmine. The molecular size, estimated from amino acid analysis and electrophoretic migration, is 65 +/- 5 amino acid residues.