Showing papers on "Sialic acid published in 1968"
TL;DR: Injection into rabbits of radioactive ceruloplasmin from which sialic acid had been removed enzymatically resulted in a rapid disappearance of the asialoceruloplAsmin from the serum and its appearance in parenchymal cells, but not in Kupffer cells, of the liver.
441 citations
TL;DR: The N-acetyl-β-glucosaminidase of human spleen has been separated by gel electrophoresis into two components, an acidic form A and a basic form B, and evidence is presented to indicate that the A form contains a number of sialic acid residues.
Abstract: 1. The N-acetyl-beta-glucosaminidase of human spleen has been separated by gel electrophoresis into two components, an acidic form A and a basic form B. 2. The two forms are readily separated on DEAE-cellulose and have been concentrated 50-fold and sevenfold respectively. 3. They show similar K(m) values towards 4-methylumbelliferyl N-acetyl-beta-d-glucosaminide, and have the same pH optima when compared in citrate, phosphate or acetate buffers. They are inhibited to a similar extent by acetate, heparin, N-acetylgalactosaminolactone, N-acetyl-beta-d-galactosamine and N-acetyl-beta-d-glucosamine. Specificity for C-4 orientation is not absolute and p-nitrophenyl beta-galactosaminide is also hydrolysed but at a rate only 11.6% of that for the corresponding glucosaminide. 4. N-Acetyl-beta-glucosaminidase B is stable over a wider pH range than is N-acetyl-beta-glucosaminidase A, and is less easily denatured by heat. 5. Tissue fractionation indicates that both the A and B forms are present in the lysosomal fraction, whereas the supernatant contains the A form only. 6. Evidence is presented to indicate that the A form contains a number of sialic acid residues.
438 citations
TL;DR: Kinetic studies indicate that Reactions A, B, and C are catalyzed by different sialyltransferases in the particulate fraction, which represents the last step in the synthesis of the major disialogangliosides from ceramide according to a proposed pathway.
149 citations
TL;DR: The purpose of this communication is to extend studies in an attempt to define the role of sialic acid in the cell periphery as a barrier to the detection of antigens on a " non specific " transplantable tumour.
Abstract: A CARBOHYDRATE-RICH protein layer has been detected on the surface of many cell types (Rambourg and Leblond, 1967; Fawcett, 1964). Bennett (1963) compared this layer to a similar coat around protozoa and he called it the glycocalyx (\" sugar-coated \"), suggesting that it may be a universal feature of animal cells. Gasic and Beydak (1961) have drawn attention to the glycocalyx of several types of experimental tumour and demonstrated that it was rich in sialic (N-acetyl neuraminic) acid. This sialic acid is the major factor determining the net negative surface charge of many animal cell types and may well be involved in the abnormal social behaviour of tumour cells in vitro (Abercrombie and Ambrose, 1962). Furthermore, it has been postulated that the sialic acid content of the periphery of tumour cells may act in some way as a barrier to the detection of antigens by the host organism and thus help to explain the immunological paradox implicit in the growth and development of potentially antigenic tumours (Currie and Bagshawe, 1967). Studies from several laboratories have recently shown that enzymatic removal of sialic acid from the surface of some transplantable mouse tumours results in great enhancement of their immunogenicity and lend support to the \" antigen-masking\" hypothesis (Currie, 1967; Lindenmann and Klein, 1967; Sanford, 1967). The purpose of this communication is to extend these studies in an attempt to define the role of sialic acid in the cell periphery as a barrier to the detection of antigens on a \" non specific \" transplantable tumour.
139 citations
TL;DR: Experiments in which enzyme was incubated with purified neuraminidase indicated that the electrophoretic heterogeneity of prostatic acid phosphatase was due to the attachment of different numbers of sialic acid residues to a single enzyme protein.
133 citations
TL;DR: The receptors prepared from BSM exhibited both conformational and size requirements although they were unusually stable to some conditions known to denature proteins, emphasize the high specificity required of the gly cosyl transferases in general for synthesis of the specific hydroxyamino acids of the BSM polypeptide receptor.
117 citations
TL;DR: There is no positive correlation between sialic acid content and loss of contact inhibition in the cell lines examined and no significant differences between the kinetic parameters for activity or feedback inhibition by uridine diphospho-N-acetylglucosamine was found.
114 citations
TL;DR: It was concluded that one enzyme was involved in formation of a fucosyl- N -acetylglucosamine linkage, probably 1–4, while the other enzyme recognized only galactose with probable formation of the α- l -fucOSyl-(1–2)- O - d -galactose linkage found in blood group substances and porcine submaxillary glycoprotein.
108 citations
TL;DR: The amino acid sequences of the glycopeptides carrying these different oligosaccharides are the same in ovotransferrin and serum transferrin, showing that the carbohydrate groups are attached to the same site on the protein molecule.
Abstract: 1. Glycopeptides were prepared from proteolytic digests of ovotransferrin and serum transferrin of the hen. The carbohydrate compositions and amino acid sequences of the peptides were studied. 2. The bulk of the carbohydrate of ovotransferrin is present as a single oligosaccharide composed of 4 residues of mannose and 8 residues of N-acetylglucosamine. Transferrin has most of its carbohydrate in a single unit composed of 2 residues of mannose, 2 residues of galactose, 3 residues of N-acetylglucosamine and either 1 or 2 residues of sialic acid. 3. The amino acid sequences of the glycopeptides carrying these different oligosaccharides are the same in ovotransferrin and serum transferrin, showing that the carbohydrate groups are attached to the same site on the protein molecule.
99 citations
98 citations
TL;DR: A neuraminidase has been partially purified by extracting calf brain acetone powder with Triton X-100 and hydrolyzed tri- and disialogangliosides as well as “hematoside”.
TL;DR: Analysis of the [1-(14)C]glucosamine-containing disaccharides released from glycogen by beta-amylase provided additional evidence that they consist of a mixture of glucose and glucosamine in a 1:1 ratio, but with glucose predominating on the reducing end.
Abstract: d-[1-(14)C]Galactosamine appears to be utilized mainly by the pathway of galactose metabolism in rat liver, as evidenced by the products isolated from the acid-soluble fraction of perfused rat liver. These products were eluted in the following order from a Dowex 1 (formate form) column and were characterized as galactosamine 1-phosphate, sialic acid, UDP-glucosamine, UDP-galactosamine, N-acetylgalactosamine 1-phosphate, N-acetylglucosamine 6-phosphate, UDP-N-acetylglucosamine, UDP-N-acetylgalactosamine and an unidentified galactosamine-containing compound. In addition, [1-(14)C]glucosamine was found in the glycogen, an incorporation previously shown to result from the substitution of UDP-glucosamine for UDP-glucose in the glycogen synthetase reaction. Analysis of the [1-(14)C]glucosamine-containing disaccharides released from glycogen by beta-amylase provided additional evidence that they consist of a mixture of glucose and glucosamine in a 1:1 ratio, but with glucose predominating on the reducing end. UDP-N-acetylgalactosamine was shown to result from the reaction of UTP with N-acetylgalactosamine 1-phosphate in the presence of a rat liver extract.
TL;DR: Two polysaccharides were isolated from the interstitial matrix surrounding the photoreceptor cells of cattle retina in a soluble form and the retinal residue left after removal is rich in amino sugar- and sialic acid-containing polymers, which appear to be firmly bound to the tissue fragments.
Abstract: 1. Two polysaccharides were isolated from the interstitial matrix surrounding the photoreceptor cells of cattle retina. They were liberated from this region of the tissue in a soluble form after agitation of whole retinas in 0.9% sodium chloride. One, which comprises two-thirds of the polysaccharides present, is a hyaluronidase-sensitive ;half-sulphated' chondroitin sulphate containing uronic acid, galactosamine and sulphate in the molar proportions 1.27:1.0:0.54. The other is a hyaluronidase-resistant non-sulphated heteropolysaccharide for which the name sialoglycan is proposed. It contains galactose, glucosamine and sialic acid in the molar proportions 2.4:1.0:0.4. Both polysaccharides contain only small amounts of nitrogen in excess of the amount calculated from their amino sugar and sialic acid content. 2. A similar combination of mucopolysaccharides is associated with the pigment epithelial-cell layer but in quantities only one-fifth of those present in the adjacent matrix area. 3. The ease with which they are released into aqueous media is consistent with the assumption that they are present in the extracellular spaces in both of these tissue layers. 4. The retinal residue left after removal of the two soluble polysaccharides is rich in amino sugar- and sialic acid-containing polymers, which appear to be firmly bound to the tissue fragments. 5. About one-third of the sialic acid and one-tenth of the amino sugar could be extracted with chloroform-methanol. The components in this fraction were tentatively identified as gangliosides. 6. Digestion of the chloroform-methanol-insoluble residue with Pronase yielded as the principal product a heteropolysaccharide containing 16.5% of glucosamine, 24.3% of neutral sugar (galactose plus fucose) and 18.1% of sialic acid. This substance has been classified as a sialoglycan of composition similar to (but not identical with) that of the soluble one isolated from the matrix area of the tissue.
TL;DR: The core oligosaccharide units showed peripheral heterogeneity in the attachment of 6- deoxy-l-galactose, 2-acetamido-2-deoxy-d-glucose and N-acetylneuraminic acid, and Tentative structures are proposed for these various types of oligosACcharide unit.
Abstract: The carbohydrate content of an A myeloma globulin was investigated. The carbohydrate content was found to be unchanged when the protein was isolated from the patient over a period of 18 months. The various polymeric forms of the protein contained similar proportions of carbohydrate. The A myeloma globulin contained approx. 2 residues of 6-deoxy-l-galactose (l-fucose), 14-15 of d-mannose, 12-13 of d-galactose, 12-13 of 2-acetamido-2-deoxy-d-glucose (N-acetyl-d-glucosamine), 6 of 2-acetamido-2-deoxy-d-galactose (N-acetyl-d-galactosamine) and 5 of N-acetylneuraminic acid (sialic acid), and these were distributed between six oligosaccharide units all of which were present on the heavy polypeptide chains. The oligosaccharide units showed two kinds of heterogeneity, which have been termed central and peripheral. Central heterogeneity was shown by the presence of three completely different core units, which had the following compositions: (1) 3 residues of d-galactose and 3 of 2-acetamido-2-deoxy-d-galactose, joined to protein by an O-glycosidic linkage between acetamidohexose and serine; (2) 3 residues of d-mannose, 2 of d-galactose and 3 of 2-acetamido-2-deoxy-d-glucose, joined to protein by an N-glycosidic linkage between acetamidohexose and aspartic acid; (3) 4 residues of d-mannose and 3 of 2-acetamido-2-deoxy-d-glucose with a linkage similar to that in (2). The core oligosaccharide units showed peripheral heterogeneity in the attachment of 6-deoxy-l-galactose, 2-acetamido-2-deoxy-d-glucose and N-acetylneuraminic acid. Tentative structures are proposed for these various types of oligosaccharide unit. Glycopeptides were isolated in which the sialic acid content exceeded that of d-galactose. Explanations are given for the electrophoretic mobility and staining characteristics of the various glycopeptides.
TL;DR: The properties of this enzyme suggest that it represents one of a group of glycosyltransferases which act to assemble the carbohydrate units of thyroglobulin, and that its function is to attach the outermost sugar, N-acetylneuraminic acid, to the galactose residues of the oligosaccharide chains.
TL;DR: It was concluded that thrombin has two polypeptide chains: the N-termini are: threonine and isoleucine.
TL;DR: It is deduced that both the malignant and the non-malignant cell possess two dissociable acid functions at the cell surface, a carboxyl group of sialic acid and another acidic group(s) of pK 3.0-4.5.
Abstract: 1. The pH–mobility relationships for saline-washed cells from a mouse strain of acute lymphoblastic leukaemia were examined before and after treatment with lower aldehydes, diazomethane and neuraminidase (EC 3.2.1.18). 2. The content of sialic acid released into the supernatant fluid of neuraminidase-treated cells was measured. 3. The stability of the charge-determining structures to temporary changes in environment (pH and ionic strength) was established. 4. Similar measurements were made on lymph-node cells obtained from non-leukaemic mice (a resistant and a leukaemia-susceptible strain were examined). 5. It is deduced that both the malignant and the non-malignant cell possess two dissociable acid functions at the cell surface, a carboxyl group of sialic acid and another acidic group(s), probably carboxyl, of p K 3·0–4·5. The malignant cells, however, have a basic dissociable function not present in the non-malignant types. 6. Suggestions are made as to how the difference in surface chemistry may be related to the problem of malignancy.
TL;DR: It was in the brains of the mentally ill that gangliosides were first discoverd, and indeed their pathologic accumulation can possibly be attributed to congenital defect of enzymes involved in their synthesis or metabolism.
Abstract: Gangliosides are found in the brain and other organs, and are composed of sphingosine, fatty acids, hexoses, and sialic acid. Types of gangliosides differ in the fatty acids and the sugar residues. The carbohydrate residue in the quantitatively predominating brain gangliosides is ganglio-N-tetraose, a tetrasaccharide. In these gangliosides, this residue combines with one or more molecules of sialic acid. The oligosaccharide part is a carrier of serologic properties. Gangliosides are characteristic lipid components of some neuronal membranes in the central nervous system, and can be localized on the synaptic apparatus of nerve cells in the cerebral cortex. Their site of occurrence and physiological action point to their participation in the transmission of impulses. It was in the brains of the mentally ill that gangliosides were first discoverd, and indeed their pathologic accumulation can possibly be attributed to congenital defect of enzymes involved in their synthesis or metabolism. Gangliosides are produced from their components by acceptor-specific transferases.
TL;DR: Alkaline hydrolysis of soluble or insoluble collagen led to the isolation of closely similar quantities of both O-Hyl-(-Gal-Glc) and O- Hyl(-Gal), thus establishing the presence of limited numbers of monosaccharide side chains in both forms of collagen.
TL;DR: Thin-layer chromatography showed that both gray and white matter have a highly abnormal pattern, with elevation of the relative proportion of four gangliosides corresponding to minor species in normal brain.
TL;DR: Study by other investigators have led to the conclusion that elastomucoproteinases attack protein-carbohydrate complexes occurring in intimate association with elastin in aorta and other tissues, and it is suggested that the glycoprotein may be identified with one of these compounds.
Abstract: 1. A glycoprotein extracted by cold alkali from the walls of human aorta was purified by chromatography on DEAE-cellulose. 2. The compound was electrophoretically homogeneous and essentially so by chromatography on DEAE-cellulose. Ultracentrifugal examination revealed two components, and it is suggested that the faster-sedimenting component represents an aggregated form of the glycoprotein. 3. Glycoprotein preparations contained approx. 8% of carbohydrate. Digestion with Pronase yielded a glycopeptide fraction containing all the carbohydrate of the glycoprotein. The glycopeptide, of molecular weight about 7800, contained sialic acid, galactose, mannose, fucose and hexosamine in the approximate molar proportions 5:10:5:2:11. Sialic acid was terminal with respect to the polysaccharide chains. 4. Both elastase and elastomucoproteinases exhibited proteolytic activity towards the glycoprotein. Studies by other investigators have led to the conclusion that elastomucoproteinases attack protein–carbohydrate complexes occurring in intimate association with elastin in aorta and other tissues, and it is suggested that the glycoprotein may be identified with one of these compounds.
TL;DR: The physiological integrity of the epididymal canal and Cowper's gland is dependent on the circulating levels of androgen, and is supported by the decreased values of sialic acid in animals with ligatures.
Abstract: Sialic acid is secreted by the testis, epididymis, ductus deferens and Cowper's gland of the male albino rat. Castration results in a considerable reduction in the sialic acid content of these organs. Androgen administration to castrated rats elevates the sialic acid levels in Cowper's gland to control values, while that of the other organs is only partially restored. This is probably due to the presence of spermatozoa in the epididymis in the control animals and is supported by the decreased values of sialic acid in animals with ligatures. The physiological integrity of the epididymal canal and Cowper's gland is thus dependent on the circulating levels of androgen.
TL;DR: It is suggested that a conjugate relationship exits between the type of sialic acid in an inhibitor, the virus strain which inhibits and the types of sIALic acid which a given viral neuraminidase will hydrolyse, which may be the basis of a sensitive test for identifying different types ofSialic acids.
TL;DR: Comparison of the sequential arrangement of monosaccharide units in Glycopeptides I and II with that of well characterized plasma glycoproteins suggests that the oligosACcharide chains in these glycopeptide lack sialic acidgalactose-N-acetylglucosamine chains, which occupy the peripheral position of the sugar units in many plasma gly coproteins.
TL;DR: It was concluded that the microheterogeneity results primarily from differences in the number and arrangement of the sialic acid residues at the surface of the molecule.
TL;DR: The carbohydrate moiety was released from the protein in the form of a glycopeptide on proteolysis with pronase and trypsin, and after purification on Sephadex, the glycoprotein was found to contain essentially all the activity of the hemagglutinin.
TL;DR: The data suggest that sialosylgalactosylceramide has no direct metabolic relationship with either the major brain gangliosides or adult brain cerebroside.
TL;DR: Examination of immunodiffusion properties of LH and TSH with antisera to each hormone yielded no evidence of cross reactivity between either bovine or human TSH and the homologous luteinizing hormones.
TL;DR: Acid mucopolysaccharides and glycoproteins from the intima and the media of 26 Japanese thoracic aortas were studied with emphasis on ageing and atherosclerosis, and changes in the compositional pattern of acid MPS with ageing or Atherosclerosis were inconclusive.
TL;DR: On the basis of gel nitration and disc electrophoretic experiments, FSH appears to be a larger and more acidic protein than LH.
Abstract: 1. Purified preparations of human pituitary follicle stimulating hormone (FSH), prepared by different procedures, have been compared with each other and with human pituitary luteinizing hormone (LH) with respect to carbohydrate content and amino acid composition. 2. FSH is a glycoprotein containing about 78% protein. Its amino acid composition is not unusual. The carbohydrate component consists of hexose, hexosamine and sialic acid. 3. Compared to LH, FSH has a relatively high content of aspartic acid, glutamic acid, glycine, alanine, phenylalanine, lysine and histidine, and a lesser content of proline, valine and tyrosine. FSH also contains 3.7 times more sialic acid and 2.9 times more hexosamine than does LH. 4. On the basis of gel nitration and disc electrophoretic experiments, FSH appears to be a larger and more acidic protein than LH. (Endocrinology 82: 109, 1968)