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At least 19 recordsLinked to original sources
PubMed1979

Purification and properties of N-acetylgalactosamine 6-sulphate sulphatase from human placenta.

1. N-Acetylgalactosamine 6-sulphate sulphatase was purified about 20000-fold from the soluble extract of human placenta with N-acetylgalactosamine 6-sulphate-glucuronic acid-N-acetyl[1-(3)H]galactosaminitol 6-sulphate as substrate in the activity assay. The enzyme appears to be a glycoprotein with a mol.wt. of about 100000 as determined by gel filtration. On gel electrophoresis in the presence of sodium dodecyl sulphate the major protein band had a mol.wt. of 78000. Variable charge heterogeneity was observed in several enzyme preparations. 2. The purified enzyme released up to one sulphate molecule from the disulphated trisaccharide. It was active towards N-acetylgalactosamine 6-sulphate and exhibited no measurable N-acetylglucosamine 6-sulphate sulphatase or any other known lysosomal sulphatase activity. Hydrolysis of [1-(3)H]galactitol 6-sulphate was achieved by incubation neither with a crude nor with a purified enzyme preparation. Chondroitin 6-sulphate and keratan sulphate, as well as heparin and heparan sulphate, served as competitive inhibitors of the enzyme. 3. Purified N-acetylgalactosamine 6-sulphate sulphatase activity was optimal at pH4.9 and 4.4 when assayed in 0.02m-sodium acetate buffer and at pH4.2 and 5.2 in 0.1m-sodium acetate buffer. A single pH-optimum at pH4.8 was observed for the crude enzyme and for the purified enzyme after mild periodate treatment. The sulphatase activity was inhibited by a variety of anions and cations and activated by thiol-specific and thiol reagents.

Chondroitinases and Chondroitin Lyases↗
PubMed1979

The occurrence of uridine diphosphate N-acetylgalactosamine 6-sulfate in quail egg white and characteristic distribution of sulfated sugar nucleotides in different avian eggs.

A sulfated sugar nucleotide has been isolated from quail egg white, and accounts for nearly 80% of the total sugar nucleotides found in the egg white. Evidence is presented that this nucleotide is uridine diphosphate N-acetylgalactosamine 6-sulfate, an isomer of the 4-sulfated derivative of uridine diphosphate N-acetylgalactosamine previously found in chicken egg white. Further studies on the distribution of sulfated sugar nucleotides in egg white of various birds (chicken, quail, pheasant, peafowl, turkey, goose, and duck) demonstrate that each species has a characteristic composition, differing from one another regarding the relative amounts of 4-sulfated, 6-sulfated, and 4,6-bissulfated derivatives of uridine diphosphate N-acetylgalactosamine.

Animals↗
PubMed1975

[Do immunization of rabbits by N-acetylgalactosamine and a disaccharide linked to a protein produce anti-microbial antibodies (author's transl)].

Rabbits were immunized with N-acetylgalactosamine linked to bovalbumine. They produced antibodies which precipitated this same sugar linked to human gamma-globulins but did not agglutinate Salmonella johannesburg which carry a side chain of N-acetylgalactosamine. The same immunization enhanced the titre of "natural" antibodies agglutinating human A red cells (which carry a terminal N-acetylgalactosamine) but they did not evoke such antibodies in rabbits with no "natural" hemagglutinins. These negative results, when compared to the positive one obtained with 0-acetyl-3,6-dideoxygalactose suggest that rabbit antibody-sites limited to one sugar may exist but that they can be detected only under certain conditions. Another group of 8 rabbits was immunized with a disaccharide alpha-Glc-(1 leads to 6)-GalNAc linked to a protein. All produced antibodies agglutinating S. johannesburg (1,40) which carry this disaccharide and S. senftenberg which carry the disaccharide alpha-Glc-(1 leads to 6)-Gal. The titres of these antibodies decreased after a second course of immunization.

ABO Blood-Group System↗
PubMed1977

Solubilization and partial characterization of UDP-N-acetylgalactosamine: globoside alpha-N-acetylgalactosaminyltransferase from dog spleen microsomes.

UDP-N-acetylgalactosamine:globoside alpha-N-acetylgalactosaminyltransferase (EC 2.4.1.-) synthesizing Forssman hapten was solubilized from dog spleen microsomes by a combination of Triton X-100 treatment and sonication. The solubilized enzyme was partially purified by calcium phosphate gel, ammonium sulfate fractionation and then DEAE-cellulose column chromatography. The enzymatic activity of the purified preparation was stimulated by exogenously added phosphatidylserine, as found in the particulate enzyme. When the properties of the purified enzyme were examined in the presence of exogenous phosphatidylserine, the enzyme had an absolute requirement for Mn2+; this was not substituted by Ca2+ or Mg2+. Apparent Km values for UDP-N-acetylgalactosamine and globoside were 1-10(-5) and 5-10(-4) M, respectively. It had a pH optimum of 6.55 regardless of the presence or absence of exogenous lipids. Since the partially purified enzyme was completely free of uridine diphosphatase which was found in the particulate preparaton, the effect of UDP on the transferase activity could be studied. Thus, UDP inhibited 85% of the activity at a concentration of 1.5 mM. p-Cholormercuribenzoate inhibited over 90% of the activity at 2 mM, indicating the transferase to be SH-enzyme.

Animals↗
PubMed1976

Biosynthesis of chondroitin sulfate. Independent addition of glucuronic acid and N-acetylgalactosamine to oligosaccharides.

Pentasaccharide 6-sulfate and hexasaccharide 6-sulfate were prepared from chondroitin 6-sulfate. Each oligosaccharide was incubated with a chick cartilage microsomal enzyme preparation and UDP [14C] glucuronic acid and/or UDP-N-[3H] acetylgalactosamine. As previously reported by other investigators, a single sugar was added from UDP-[14C] glucuronic acid to the nonreducing end of pentasaccharide 6-sulfate and from UDP-N-[3H] acetylgalactosamine to the nonreducing end of hexasaccharide 6-sulfate. The labeled oligosaccharides were characterized by gel chromatography and degradation by chondroitinase ABC followed by identification of products. The oligosaccharides in concentrations above their Km inhibited chondroitin synthesis on endogenous primers, reinforcing the assumption that the enzymes involved in the additions to exogenous oligosaccharides are the same as those involved in chondroitin polymerization. When either the pentasaccharide 6-sulfate or hexasaccharide 6-sulfate was incubated in reaction mixtures containing both of the sugar nucleotides there was generally growth of oligosaccharide by two or three sugars. With longer incubation under conditions of limiting oligosaccharide concentration, as many as 14 to 16 sugars could be added but no further chondroitin polymerization took place. Addition of each sugar was shown to depend upon the concentration of appropriate acceptor but was otherwise independent of the addition of the alternate sugar. No paired addition of sugars was noted. It was concluded that two specific enzymes are involved in alternate additions of sugars to the oligosaccharides and that the two enzymes have no apparent interaction with one another. It is suggested that the rapid polymerization to form large chondroitin chains which previously has been shown to take place on endogenous primers is facilitated by interaction of the two enzymes with a component of the endogenous primer. This component is not present in the exogenous oligosaccharides since they do not serve in the same fashion as primers for polymerization.

Acetylgalactosamine↗
PubMed1976

N-acetylgalactosamine-6-sulfate sulfatase in man. Absence of the enzyme in Morquio disease.

Human N-acetylgalactosamine-6-sulfate sulfatase (6-sulfatase) activity is measured by using as a substrate a sulfated tetrasaccharide obtained by digesting purified chondroitin-6-sulfate (C-6-S) with testicular hyaluronidase. The amount of inorganic sulfate released is measured turbidimetrically. The enzyme from human kidney has a pH optimum of 4.8; its activity is augmented by low levels of NaCl and inhibited by phosphate and high levels of NaCl. Free glucuronate, acetylgalactosamine, inorganic sulfate, polymeric C-6-S, or tetrasaccharide obtained from chondroitin-4-sulfate do not affect the enzyme activity. The method may be used for the diagnosis of Morquio disease since extracts of Morquio fibroblasts are devoid of 6-sulfatase activity.

Chondroitin Sulfates↗
PubMed2026

Molecular Mobility of N-Acetylgalactosamine-Modified Cyclodextrins on a Polyrotaxane for Highly Efficient Liver Targeting of Antibody Chimeras and Genome-Editing Ribonucleoproteins.

Triantennary N-acetylgalactosamine (triGalNAc), which interacts strongly with the trimeric structure of asialoglycoprotein receptors (ASGPRs), is a validated platform for liver targeting. However, the intricate design and synthesis of its linkers impose high production costs and significant technical challenges. In this study, we report an alternative strategy for targeting ASGPR using monovalent GalNAc (monoGalNAc) conjugated to the cyclic molecules of polyrotaxane, which can rotate and translocate along the axial polymer chain. The intracellular uptake efficacy of monoGalNAc-modified polyrotaxane is comparable to that of triGalNAc-modified polyrotaxane and significantly higher than that of triGalNAc- or monoGalNAc-modified immobile control polymers. These results suggest that the inherent mobility of polyrotaxanes allows monoGalNAc moieties to cluster in a trivalent-like manner, thereby enhancing multivalent interactions with multiple ASGPR oligomers. The successful application of monoGalNAc-modified polyrotaxane to lysosome-targeting antibody chimeras and genome-editing nanoparticles demonstrates that this facile technology is a highly promising alternative to conventional triGalNAc.

Rotaxanes↗
PubMed1977

Glycoproteins are modified in the axon of R2, the giant neuron of Aplysia californica, after intra-axonal injection of [3H]N-acetylgalactosamine.

We have found evidence that mechanisms exist in the axon by which proteins, originally synthesized in the cell body, can be modified. Incorporation of [3H]N-acetyl-D-galactosamine into macromolecules was studied in the axon of R2, the giant identified neuron of the abdominal ganglion of Aplysia. The precursor sugar, injected directly into the major axon in the right connective, labeled both glycoproteins and glycolipids. These macromolecules were associated with membranes and at least 90% of the incorporated radioactivity could be sedimented by centrifugation at 105,000 X g. Radiocutography of injected axons with the light microscope showed that most of the silver grains were located over the axon rather than over other tissues in the right connective. Grains appeared over a variety of axonal components, but quantitative electron microscopic radioautography revealed that vesicles were the only organells significantly labeled. Disco polyacrylamide gel electrophoresis in sodium dodecyl sulfate (SDS) of the membrane fraction resolved [5-(3)H]glycoprotein components. These membrane glycoproteins ranged in apparent molecular weight from 20,000 to 160,000 daltons and could be digested by pronase. Only one component had a mobility similar to that of a glycoprotein found in the axon after injection of the cell body. Incorporation of [3H]N-acetylgalactosamine into axonal glycoprotein was unaffected by anisomycin, a potent inhibitor of protein synthesis in Aplysia, and therefore presumably occurred on already existing polypeptide chains. We conclude that these were synthesized in the cell body and exported into the axon where they were modified by the addition of sugar.

Acetylgalactosamine↗
PubMed1979

Gangliosides of human erythrocytes. A novel ganglioside with a unique N-acetylneuraminosyl-(2 leads to 3)-N-acetylgalactosamine structure.

A novel ganglioside having both N-acetylgalactosamine and N-acetylglucosamine was isolated from human erythrocyte membranes. Its structure was characterized by successive exoglycosidase treatment, methylation analysis, and direct-probe mass spectrometry of permethylated intact and desialylated glycolipid. The core structure of the ganglioside was found to be N-acetylgalactosaminyl paragloboside with sialosyl substitution by 2 leads to 3 linkage at the terminal GalNAc residue: NeuNAc alpha 2 leads to 3 GalNAc beta 1 leads to -3Gal beta 1 leads to 4 GlcNAc beta 1 leads to 3 Gal beta 1 leads to 4Glc leads to Cer. The ganglioside was characterized by the presence of a ceramide with myristic acid as the major component.

Acetylgalactosamine↗
PubMed1977

Myxospore coat synthesis in Myxococcus xanthus: enzymes associated with uridine 5'-diphosphate-N-acetylgalactosamine formation during myxospore development.

Activities of the enzymes glutamine synthetase (EC 6.3.1.2.), glucosamine 6-phosphate acetyltransferase (EC 2.3.1.4.), uridine 5'-diphosphate (UDP)-N-acetylglucosamine pyrophosphorylase (EC 2.7.23.), UDP-N-acetylglucosamine 4-epimerase (EC 5.1.3.7.), fructose 1,6-diphosphate phosphatase (EC 3.13.11.), L-glutamine-fructose 6-phosphate transamidase (EC 5.3.1.19.), alkaline phosphatase (EC 3.1.3.1.), and malic dehydrogenase (EC 1.1.1.37) were assayed in partially purified extracts prepared at different stages of myxospore formation and germination in liquid cultures of Myxococcus xanthus. The specific activities of the first six of these enzymes increased 4.5- to 7.5-fold after 2 h of induction with 0.5 M glycerol or 0.2 M dimethyl sulfoxide. The increase in specific activities of these six enzymes was not observed in a mutant unable to be induced with glycerol. During the first 2 to 4 h of induction and during the first hour of germination, the level of these enzymes decreased to the level characteristic of vegetative cells. It is suggested that the six enzymes are responsible for the increased conversion of fructose 1,6-diphosphate to UDP-N-acetylgalactosamine, the major precursor of the myxospore coat.

Acetylglucosamine↗
PubMed1977

Binding of N-acetylgalactosamine-containing compounds by a human IgM paraprotein.

A serum that contains a monoclonal human IgM paraprotein (McG) agglutinates protease-treated human erythrocytes and binds glycosphingolipids that possess a terminal nonreducing N-acetylgalactosaminyl residue in either the alpha or beta anomeric configuration. The approximately equal reactivity of McG with both anomers of N-acetylgalactosamine was unexpected because most immunoglobulins that bind saccharides exhibit a marked preference for one anomeric configuration. The major receptor for this protein in normal group O erythrocytes is globoside, the blood group P antigen: Ga1NAc( beta, 1 leads to 3)Gal(alpha,1 leads to 4)Gal(b,1 lead to 4)G1c-ceramide. Erythrocytes of the rare Pk and p phenotypes lack globoside, and the former are not agglutinated by McG. The McG receptor in p erythrocytes, which are agglutinated as strongly as normal cells, appears to be a crossreactive glycolipid that contains a much larger number of sugar residues than globoside.

ABO Blood-Group System↗
PubMed1978

Enzymatic formation of UDP-N-acetylgalactosamine in epiphysial-plate cartilage.

The activity of UDP-N-acetylglucosamine 4'-epimerase (EC 5.1.3.7) from newborn pig epiphysial-plate cartilage was investigated. The formation of radioactive UDP-N-acetylgalactosamine from UDP-N-acetyl[U-14C]-glucosamine was demonstrated by radioautography, after hydrolysis of UDP-derivatives and separation of the hexosamines by paper chromatography. The pH optimum and the Km values for UDP-N-acetylglucosamine and NAD were determined. At equilibrium, the ratio UDP-N-acetylglucosamine/UDP-N-acetylgalactosamine reaches a value of about 2.3. The effect of UDP-xylose and UDP-glucuronic acid on the enzyme activity was investigated. NADH inhibits UDP-N-acetylglucosamine 4'-epimerase activity. The inhibitory effect of NADH seems to be strikingly correlated with the value of NAD/NADH ratio and pH.

Animals↗
PubMed1977

Ovine submaxillary mucin. Primary structure and peptide substrates of UDP-N-acetylgalactosamine:mucin transferase.

Tryptic digests of ovine submaxillary apomucin were fractionated by gel filtration and ion exchange chromatography to give 14 peptide fractions. Three purified tryptic peptides, representing 106 of the 650 residues in apomucin, were submitted to automated sequence analysis. The NH2-terminal 50 of the 74 residues in one peptide and the entire sequence of the other two hexadecapeptides were established. These studies suggest that purified ovine submaxillary, mucin is chemically homogeneous, containing a unique primary structure without substantial repeating sequences in its polypeptide chain. The sequences adjacent to 28 known O-glycosidically substituted seryl and threonyl residues were compared. No homologies were apparent around the glycosylated seryl and threonyl residues which might define the specificity of the UDP-N-acetylgalactosaminyl:mucin polypeptide transferase that incorporates N-acetylgalactosamine into O-glycosidic linkage in glycoproteins. However, there appears to be a minimum size requirement for glycosylation, because the transferase catalyzes glycosylation of tryptic peptides efficiently, while chymotryptic and thermolytic peptides were much poorer substrates for the transferase.

Amino Acid Sequence↗
PubMed1979

Hybrid glycosaminoglycans synthesized by monolayers of chick embryo arterial fibroblasts.

Monolayer cultures of arterial fibroblasts from 13-day chick embryonic aorta incorporated 35SO42- into glycosaminoglycans containing both glucuronic and iduronic acids. Bacterial chondroitinase ABC converted more than 98% of the 35SO4-labeled polymer to mono- or disaccharides, including (1) N-acetyl-D-galactosamine 4-sulfate, (2) delta 4,5-glucuronic acid 2- or 3-sulfate leads to N-acetylgalactosamine 6-sulfate, and (3) the unsaturated disaccharides normally obtained from chondroitin 4-sulfate and chondroitin 6-sulfate sequences. Chondroitinase AC converted only 77% of the 35SO4-labeled polymer to the same mono- and disaccharides and yielded, in addition, the following oligosaccharide products: (1) delta 4,5-glucuronic acid leads to N-acetylgalactosamine 4- or 6-sulfate leads to iduronic acid leads to N-acetylgalactosamine 6- or 4-sulfate; (2) N-acetylgalactosamine 4-sulfate leads to iduronic acid 2- or 3-sulfate leads to N-acetylgalactosamine 6-sulfate; (3) delta 4,5-glucuronic acid leads to N-acetylgalactosamine 4-sulfate leads to (iduronic acid leads to N-acetylgalactosamine 4-sulfate)2; (4) delta 4,5-glucuronic acid leads to N-acetylgalactosamine 4- or 6-sulfate leads to (iduronic acid leads to N-acetylgalactosamine 6- or 4-sulfate)2; (5) higher oligosaccharides containing iduronic acid and N-acetylgalactosamine 4-sulfate.

Animals↗
PubMed1976

Effects of uridine nucleotides and nucleotide pyrophosphatase on glycolipid alpha and beta-N-acetylgalactosaminyltransferase activities in guinea pig microsomes.

Membrane-bound alpha and beta-N-acetylgalactosaminyltransferases (EC 2.4.1.0) which catalyze formation of non-reducing terminal linkages of Forssman hapten and globoside, respectively, could be differentiated with respect to the different effects of UDP on the two enzyme activities. UDP markedly inhibited the alpha-transferase activity, in contrast to its stimulatory action on the beta-transferase. These effects of UDP were similar to those of UDPglucose, which was demonstrated to be a competitive inhibitor (Ki, 3.3 - 10(-5) M for UDP-N-acetylgalactosamine) for the alpha-transferase reaction. Other uridine derivatives tested suppressed both the transferase activities, being more inhibitory for the alpha-transferase than for the beta-transferase. Under the synthetic conditions of these aminoglycolipids, UDP-N-acetylgalactosamine as a donor was simultaneously degraded into N-acetylgalactosamine-1-phosphate and finally into N-acetylgalactosamine by UDP-N-acetylgalactosamine pyrophosphatase, which is part of the membrane system. UDPglucose was confirmed as being able to prevent the enzymatic hydrolysis of UDP-N-acetylgalactosamine. UDPglucose, therefore, acts to suppress both the alpha-N-acetylgalactosaminyltransferase (but not the beta-transferase) and the pyrophosphatase activities. The inhibitory effect of UDPglucose on the alpha-transferase activity was most probably due to its direct action on the transferase rather than its function in protecting UDP-N-acetylgalactosamine donor from pyrophosphatase action.

Animals↗
PubMed1978

Hydrolysis of sugar nucleotides in chicken egg white in response to embryonic development.

The egg white of newly laid chicken egg was found to contain about 45 mumol of UDP-N-acetylgalactosamine 4-sulfate, 34 mumole of GDP-mannose, 6 mumol of UDP-N-acetylhexosamine, and 1 mumol of UDP-N-acetylgalactosamine 4,6-bissulfate per liter. There was no significant difference between infertile and fertile eggs in the initial levels of the sugar nucleotides. During incubation for 4 days, the nucleotide levels in infertile eggs showed little change while those in fertile eggs fell continuously until the complete disappearance of the nucleotides on the fourth day. Initial removal of the blastoderm from fertile eggs resulted in cessation of the reduction in nucleotide levels in the 2- to 4-day period after the operation. The decrease of UDP-N-acetylgalactosamine 4-sulfate was followed by an increase of 1-phospho-N-acetylgalactosamine 4-sulfate then N-acetylgalactosamine 4-sulfate in the egg white. When UDP-N-acetylgalactosamine 4-[35S]sulfate or GDP-[14C]mannose was injected into the egg white of a fertile egg, the main feature of the metabolism of the labeled compounds was the successive hydrolysis of their pyrophosphate and phosphate bonds, with the formation of sugar 1-phosphate and sugar. A significant activity of nucleotide pyrophosphatase was detected in the egg white in newly laid eggs (0-day egg). However, no such activity could be detected in egg-white specimens from 1-, 2-, and 3-day eggs. The results suggest that although the decrease of sugar nucleotides in the first day could be ascribed to the hydrolytic action of the enzyme originally present in the egg white, the decrease in the subsequent 3 days results from a more complex process in which the hydrolysis of the sugar nucleotides is related to the development of the embryo.

Acetylgalactosamine↗