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PubMed1988

Human beta-mannosidase deficiency: biochemical findings in plasma, fibroblasts, white cells and urine.

Marked deficiencies of beta-mannosidase activity were demonstrated in plasma, leukocytes, fibroblasts and urine of a patient with beta-mannosidosis, similar deficiencies were observed in the proband's sibling. All other lysosomal enzymes measured, including sulphamidase, exhibited normal activity. Both parents showed reduced plasma and leukocyte beta-mannosidase activity. Urinary glycosaminoglycan excretion was normal but TLC of urinary oligosaccharides revealed an abnormal band with the mobility of a disaccharide. This finding was confirmed by Bio-Gel P2 column chromatography. Further purification of this compound revealed two disaccharides, both of which yielded mannose and glucosamine following acid hydrolysis and mannose and N-acetylglucosamine following enzymic digestion. These two compounds are thought to be structural isomers of the disaccharide Man beta-GlcNAc.

Adult↗
PubMed2004

Purification and characterization of recombinant Escherichia coli-expressed Pichia etchellsii beta-glucosidase II with high hydrolytic activity on sophorose.

Beta-glucosidase II (Bgl II), encoded by the betaglu2 gene of the thermo-tolerant yeast Pichia etchellsii, was purified from recombinant Escherichia coli pBG22:JM109. The enzyme had a molecular mass of 176 kDa and was a dimer with an apparent subunit mass of 83 kDa. It exhibited broad substrate specificity and hydrolyzed beta-linked gluco-disaccharides and oligosaccharides, salicin, and cyanogenic glucoside amygladin. The unusually high hydrolytic activity of 7,680 units min(-1) g(-1) protein was obtained on sophorose. Competition experiments performed using differently linked beta-disaccharides indicated these to be hydrolyzed at the same active site. Transglycosylation activity leading to the biosynthesis of several disaccharides and oligosaccharides was observed. The enzyme was placed in glycosyl hydrolase family 3, based on a statistical approach using amino acid composition data. The involvement of His as a catalytically important residue was confirmed by diethylpyrocarbonate modification. Pre-incubation of the purified enzyme with 5 mM p-nitrophenyl-beta-D-glucoside offered 2.5-fold higher residual activity compared with unbound enzyme, indicating protection at the active site. The feasibility of this enzyme as a biocatalyst of choice for the synthesis of glyco-conjugates is discussed.

Cloning, Molecular↗
PubMed2005

Polyvalent GalNAcalpha1-->Ser/Thr (Tn) and Galbeta1-->3GalNAcalpha1-->Ser/Thr (T alpha) as the most potent recognition factors involved in Maclura pomifera agglutinin-glycan interactions.

The agglutinin isolated from the seeds of Maclura pomifera (MPA) recognizes a mucin-type disaccharide sequence, Galbeta1-->3GalNAc (T) on a human erythrocyte membrane. We have utilized the enzyme-linked lectinosorbent assay (ELLSA) and inhibition assay to more systematically analyze the carbohydrate specificity of MPA with glyco-recognition factors and mammalian Gal/GalNAc structural units in lectin-glycoform interactions. From the results, it is concluded that the high densities of polyvalent GalNAcalpha1-->Ser/Thr (Tn) and Galbeta1-->3GalNAcalpha1-->Ser/Thr (T(alpha)) glycotopes in macromolecules are the most critical factors for MPA binding, being on a nanogram basis 2.0 x 10(5), 4.6 x 10(4) and 3.9 x 10(4) more active than monovalent Gal, monomeric T and Tn glycotope, respectively. Other carbohydrate structural units in mammalian glycoconjugates, such as human blood group Sd (a+) related disaccharide (GalNAcbeta1-->4Gal) and Pk/P1 active disaccharide (Galalpha1-->4Gal) were inactive. These results demonstrate that the configurations of carbon-4 and carbon-2 are essential for MPA binding and establish the importance of affinity enhancement by high-density polyvalencies of Tn/T glycotopes in MPA-glycan interactions. The overall binding profile of MPA can be defined in decreasing order as high density of polyvalent Tn/T(alpha) (M.W. > 4.0 x 10(4)) >> Tn-containing glycopeptides (M.W. < 3.0 x 10(3)) > monomeric T/Tn and P (GalNAcbeta1-->3Gal) > GalNAc > Gal >> Man, L: ARA: , D: Fuc and Glc (inactive). Our findings should aid in the selection of this lectin for elucidating functions of carbohydrate chains in life processes and for applications in the biomedical sciences.

Animals↗
PubMed1986

The solution structure of mucous glycoproteins: proton NMR studies of native and modified ovine submaxillary mucin.

The solution structure of native and systematically modified ovine submaxillary mucin (OSM) has been probed by proton NMR spectroscopic methods. Most of the resonances in the spectra have been tentatively assigned to the peptide and O-linked disaccharide, alpha-N-acetylneuraminic acid 2----6 alpha-N-acetylgalactosamine protons. On the basis of the observed chemical shifts, spectral resolution, and behavior of the exchangeable protons it is concluded the mucin possesses internal segmental flexibility and exists in solution as a random coil peptide. No long-lived interresidue peptide or carbohydrate hydrogen bonds were detected. The removal of (i) the C8 and C9 carbons of the sialic acid residue, (ii) the entire sialic acid residue, and (iii) the complete disaccharide side chain resulted in no significant changes in peptide core conformation. A limited set of proton spin coupling constants and nuclear Overhauser enhancements has been obtained for the threonine glycopeptide side chains in native and modified mucin. The results are consistent with the previously reported conformations for the (1----6) linkage in oligosaccharides and the threonyl glycosidic linkage in glycopeptides. The OSM disaccharide may exist as a extended linear structure with rotational freedom about the GalNAc C5-C6 bond, while the threonine glycosidic linkage appears to be sterically constrained, although multiple conformations about the threonine C beta-O gamma bond may be allowed. The small chemical shift perturbations detected in the glycosylated threonine methyl protons and the GalNAc carbons upon removal of the terminal sialic acid residue are consistent with this model.

Animals↗
PubMed1975

The specificity of the synthetic reaction of two yeast alpha-glucosidases.

The specificity of the hydrolytic reaction has been compared to that of the synthetic reaction for maltase and isomaltase (alpha-methyl-D-glucosidase) from Saccharomyces oviformis. Maltase which hydrolyzes the alpha-1,4-disaccharide, maltose, and the alpha-1,6-disaccharide, isomaltose, catalyzes the formation of both maltose and isomaltose from free glucose. Isomaltase, which hydrolyzes isomaltose but not maltose, catalyzes the formation only of isomaltose from glucose. Both enzymes hydrolyze p-nitrophenyl-alpha-D-glucoside releasing the alpha-anomer of glucose. The enzymes utilize the alpha-anomer but not the beta-anomer for the synthesis of the disaccharides. These results are consistent with the double displacement mechanism for glycosidases and with the proposal that the glucosyl-enzyme complex is an intermediate in the reaction. The competitive inhibition by D-glucose is independent of its anomeric form for both enzymes.

Borohydrides↗
PubMed1981

Novel polar lipids from the methanogen Methanospirillum hungatei GP1.

The methanogenic bacterium Methanospirillum hungatei GP1 has been shown to contain two unusual phosphoglycolipids (phosphoglycolipid I and phosphoglycolipid II) that account for 64% (by wt.) of the total cellular lipids. These lipids are derivatives of the dibiphytanyldiglycerol tetraether. One of the free hydroxyls of this tetraether is esterified with glycerophosphoric acid and the other is linked glycosidically to a disaccharide with structure alpha-Glcp-(1 leads to 2)-beta Gal phi in phosphoglycolipid I and beta-Gal phi-(1 leads to 6)-beta Gal phi in phosphoglycolipid II. Smaller amounts of the sn-2,3-diphytanylglycerol analog of phosphatidylglycerol and diglycosyldiphytanylglycerol ethers (DGD-I and DGD-II) containing the same disaccharide residues as in phosphoglycolipid I and phosphoglycolipid II, respectively, were identified, together with very small amounts of diglycosyldibiphytanyldiglycerol tetraethers (DGT-I and DGT-II) containing the same disaccharide residues as in phosphoglycolipid I and phosphoglycolipid II, respectively. A biosynthetic pathway involving head-to-head condensation of phosphatidylglycerol with DGD-I or DGD-II to form phosphoglycolipid I or phosphoglycolipid II, respectively, is proposed.

Carbohydrate Conformation↗
PubMed1984

Synthetic mucin fragments: benzyl 2-acetamido-6-O-(2-acetamido-2-deoxy-beta- D-glucopyranosyl)-2-deoxy-3-O-beta-D-galactopyranosyl-alpha-D- galactopyranoside and benzyl 2-acetamido-6-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)- 3-O-[6-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-beta-D- galactopyranosyl]-2-deoxy-alpha-D-galactopyranoside.

Glycosylation of benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-alpha-D- galactopyranoside with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide, catalyzed by mercuric cyanide, afforded benzyl-2-acetamido-4,6-O-benzylidene-2-deoxy-3- O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-alpha-D- galactopyranoside (3). O-Deacetylation of 3 gave benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-3-O-beta- D-galactopyranosyl-alpha-D-galactopyranoside which, on acetalation with benzaldehyde-zinc chloride complex followed by acetylation of the resulting dibenzylidene acetal, gave the disaccharide diacetate (7). Cleavage of the acetal groups of 3 and 7 in hot, 80% aqueous acetic acid furnished, respectively, the disaccharide tetraacetate (4) and diacetate (8). O-Deacetylation of 8 in methanolic sodium methoxide gave the disaccharide (9). Condensation of 4 or 8 with 2-methyl-(3,4,6-tri-O-acetyl-1,2- dideoxy-alpha-D-glucopyrano)-[2,1-d]-2-oxazoline, followed by O-deacetylation, afforded the title tri- and tetra-saccharides, 12 and 14, respectively. The structures of compounds 9, 12, and 14 were established by 13C-n.m.r. spectroscopy.

Indicators and Reagents↗
PubMed1984

Immunochemical characterization of the specificities of two human monoclonal IgM's reacting with chondroitin sulfates.

We have studied the specificities of two human monoclonal, IgM containing sera, s/IgMMAC and s/IgMFIS, from patients with polyneuropathy. s/IgMMAC precipitates only with chondroitin sulfate C and not with A and B whereas s/IgMFIS is precipitated by chondroitins A, B (dermatan sulfate), and C. Inhibition assays using 2-acetamido-2-deoxy-3-O-(4-deoxy-beta-L-threo-hex-4-enopyranosyluroni c acid)-D-galactose and its 6- and 4-sulfate derivatives showed that the disaccharide 6-sulfate was the best inhibitor of precipitation of s/IgMMAC by chondroitin sulfate C, and the disaccharide 4-sulfate the best inhibitor of precipitation of s/IgMFIS by either chondroitin sulfates C or B. The nonsulfated disaccharide was a good inhibitor in each instance. D-Glucose 6-sulfate, Na2SO4, several sugar phosphates, and phosphate buffer also inhibited but to different extents with the s/IgMMAC and s/IgMFIS. All studies were carried out in 0.15M NaCl. The data indicate that both monoclonal proteins are antibodies comparable to the phosphorylcholine-binding myeloma proteins, and that the reactions show specificities above and beyond charge effects. The relation of various cross-reacting macromolecules to the monoclonal antibody was studied by diffusion in gels.

Antibodies, Monoclonal↗
PubMed1986

Structural differences of dermatan sulfates from different origins.

The dermatan sulfates from hog, rat, rabbit, and beef liver, hog, rat, beef, and dog spleen, and hog skin were isolated and submitted to structural analysis. All of them migrated as single bands, close to the standard position for dermatan sulfate in agarose-gel electrophoresis. In polyacrylamide gel, however, each dermatan sulfate showed a characteristic electrophoretic migration-pattern: one, two, or three polydisperse bands, corresponding to different molecular weights, were obtained for the dermatan sulfates according to their origins. Chemical analysis showed that all of the dermatan sulfates here described are hybrid polymers composed of D-glucuronic and L-iduronic acid-containing disaccharide units. The relative position of these units in the polymer chains and the presence of 6-sulfated disaccharides were determined with the aid of chondroitinases B and AC from Flavobacterium heparinum. These studies show that each dermatan sulfate has a unique structure as regards the molecular weight, the presence of 6-sulfated disaccharide units, and also the relative amount and position of glucuronic and iduronic acid residues in the chains. These findings suggests a tissue- and species-specificity for the dermatan sulfates.

Animals↗
PubMed1990

Synthesis of a tetrasaccharide of the genus-specific lipopolysaccharide epitope of Chlamydia.

Allyl 2-acetamido-2-deoxy-3,4-O-(1,1,3,3-tetraisopropyldisiloxan-1,3- diyl)-beta-D- glucopyranoside was coupled with methyl (4,5,7,8-tetra-O-acetyl-3-deoxy-alpha-D-manno-2-octulopyranosyl bromide)onate (1) to give a good yield of the alpha-(2----6)-linked disaccharide, isolated after deacetylation and regioselective conversion into the corresponding 7',8'-O-carbonyl or 7',8'-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl) derivatives, respectively. Subsequent glycosylation with 1 gave a high yield of the alpha- and beta-(2"----4')-linked trisaccharide derivatives 16 and 18, whereas block synthesis using the alpha-(2----8)-linked Kdo-disaccharide bromide derivative 19 afforded a low yield of the corresponding alpha- and beta-(2"----4')-linked tetrasaccharide derivatives 20 and 22. Removal of the protecting groups furnished the disaccharide allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2----6)-2-acetamido -2-deoxy- beta-D-glucopyranoside, the trisaccharide allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2----4)-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2----6)-2-acetamido -2-deoxy- beta-D-glucopyranoside, and the tetrasaccharide allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2----8)-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2----4)-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2----6)-2-acetamido -2-deoxy- beta-D-glucopyranoside in high yield. Copolymerization of the allyl glycosides with acrylamide gave artificial polyvalent haptens suitable for defining epitope specificities of monoclonal antibodies directed against Chlamydia lipopolysaccharides.

Antibody Specificity↗
PubMed1993

Synthesis of the laminara-oligosaccharide methyl beta-glycosides of dp 3-8.

Ethyl 2,3,4,6-tetra-O-acetyl-1-thio-alpha-D-glucopyranoside has been prepared in a good yield by anomerization of the corresponding beta-thioglucoside with tin(IV) chloride and transformed, in three steps, into ethyl 2-O-benzoyl-4,6-O-benzylidene-1-thio-alpha-D-glucopyranoside (18). Chloroacetylation of 18, followed by treatment of the product with chlorine gave crystalline 2-O-benzoyl-4,6-O-benzylidene-3-O-chloroacetyl-beta-D-glucopyranosyl chloride (20). This was coupled with methanol in the presence of silver carbonate-silver perchlorate and the product was O-dechloroacetylated to afford methyl 2-O-benzoyl-4,6-O-benzylidene-beta-D-glucopyranoside (22). Silver triflate-promoted glucosylation of 18 with 20 gave a beta-(1-->3)-linked disaccharide derivative, reaction of which with chlorine yielded crystalline O-(2-O-benzoyl-4,6-O-benzylidene-3-O-chloroacetyl-beta-D-glucopyranosyl) - (1-->3)-2-O-benzoyl-4,6-O-benzylidene-beta-D-glucopyranosyl chloride (24). Likewise, condensation of 22 with 20 gave a beta-(1-->3)-linked disaccharide glycoside, which was partially deprotected to give methyl O-(2-O-benzoyl-4,6-O-benzylidene-beta-D-glucopyranosyl)-(1-->3)-2-O-benz oyl- 4,6-O-benzylidene-beta-D-glucopyranoside (26). The methyl beta-glycosides of a homologous series of (1-->3)-linked beta-D-gluco-oligosaccharides from the tri- to the octa-saccharide have been synthesized in a blockwise manner by using 22 and 26 as the glycosyl acceptors, 24 as the disaccharide donor, and silver triflate as the promoter.

Carbohydrate Conformation↗
PubMed1981

The diagnosis of the Sanfilippo C syndrome, using monosaccharide and oligosaccharide substrates to assay acetyl-CoA: 2-amino-2-deoxy-alpha-glucoside N-acetyltransferase activity.

Glucosamine, galactosamine, mannosamine, several disaccharides and a tetrasaccharide were evaluated as substrates for the N-acetyltransferase involved in the pathogenesis of the Sanfilippo C syndrome. Glucosamine and alpha-D-glucosaminide disaccharides and a tetrasaccharide derived from heparin were exo-N-acetylated by homogenates of cultured skin fibroblast from normal individuals at pH 6.0 in the presence of acetyl-CoA, whereas fibroblast homogenates prepared from a Sanfilippo C patient failed to catalyse the N-acetyltransferase from acetyl-CoA to these substrates. The apparent Km values of the glucosamine and alpha-glucosaminide disaccharide N-acetyltransferase were 98 and 200 mumol/l respectively; the corresponding V values were 200 and 180 nmol.min-1.g-1 fibroblast whole cell homogenate protein respectively. Incubation of homogenates from normal individuals or the Sanfilippo C patient with glucosamine 6-phosphate and acetyl-CoA at pH 6.0 produced N-acetylglucosamine 6-phosphate. Acetyltransfer to glucosamine or glucosamine 6-phosphate in homogenates of normal fibroblasts was not inhibited by the addition of arylamines. It is proposed that N-acetyltransferase to glucosamine, glucosamine 6-phosphate and arylamines is carried out by separate enzymes. Glucosamine is a suitable substrate for the diagnostic assay of the enzyme involved in the exo-N-acetylation of alpha-glucosaminide residues at the non-reducing end of the heparan sulfate stored and excreted by Sanfilippo C patients.

Acetyltransferases↗
PubMed1990

Chondroitin 4-sulfate proteoglycan forms an extracellular network in human and rat central nervous system.

Chondroitin 4-sulfate proteoglycan (C4S-PG) was localized both in rat and human central nervous system (CNS) by monoclonal and polyclonal antisera recognizing the 4-sulfate disaccharide (C4S). In the rat the whole CNS was studied in serial coronal sections. A positive extracellular meshwork was observed both in white and grey matters. In the white matter (WM) C4S-PG formed a network around myelinated axons, sparing myelin sheaths and axoplasms. The neuropil of the grey matter (GM) showed a positive meshwork constituted by delicate intermingling filaments. The cytoplasms of neuronal, glial and endothelial cells were negative. Stronger straining than in the neuropil was observed around the soma and the proximal part of the cell processes of some neurons located in the cortex, in the deep cerebellar nuclei and in some other CNS nuclei. A similar pattern was also observed in human CNS, the only difference being a smaller amount of cortical neurons surrounded by a rim of C4S-PG. This study shows that a PG bearing C4S disaccharide is located extracellularly in the rodent and human CNS and that C4S disaccharides can be present in different types of CNS proteoglycans (PGs).

Aged↗
PubMed1992

Identification of peanut agglutinin receptors related to the state of tumoral liver cell differentiation.

The relationship between cell differentiation/tumorisation and plasma membrane glycoproteins was approached using peanut agglutinin (PNA) a lectin specific for the Gal-beta(1,3)GalNAc sequence and a homologous cell system consisted of normal rat hepatocytes (HyC) and a poorly differentiated hepatoma (ZHC). This work is focused on the molecular nature of PNA receptors. PNA bound strongly to ZHC, but bound very weakly, if at all to hepatocytes. After sialidase treatment this binding was slightly enhanced in ZHC and HyC. The total number of binding sites on ZHC was 9.6 x 10(6)/cell and 1.2 x 10(7)/cell before and after sialidase treatment respectively. In contrast, this number could not be calculated on HyC, even after sialidase treatment. The PNA receptors were isolated and identified from ZHC using affinity chromatography on immobilized PNA and lectin overlay. Two bands were revealed after SDS-PAGE of PNA receptors: a major one with a relative molecular mass of 160 kDa and a minor one of 110 kDa. The latter disappeared after sialidase treatment of ZHC suggesting the possibility that these two bands could be less and more sialylated forms of the PNA receptors, respectively. In contrast no PNA receptors could be detected on HyC. These PNA receptors could be considered O-linked glycoproteins containing the Gal-beta(1,3)GalNAc disaccharide because: i) PNA carbohydrate specificity toward this disaccharide found in this glycoprotein type; ii) their carbohydrate composition with Gal and GalNAc but not man residues; iii) their sensitivity to alkaline treatment; and iv) strong inhibition of PNA binding to ZHC with the Gal-beta(1,3)GalNAc structure. The absence of PNA receptors on HyC appeared to be related to the absence of this glycoprotein containing the disaccharide but not to the change or failure of glycosylation of the polypeptide chain of PNA receptors. The relationship between the presence of PNA receptors and differentiation/tumorisation phenomena as well as the mechanism that induced the expression of these receptors are discussed.

Animals↗
PubMed1976

Biosynthesis of chondroitin sulfate side chains and hyaluronate. Time-course studies with cartilage slices of calf ribs under different conditions.

The time course of double labeling with 35SO24- and [3H]glucosamine was followed in a semi-in vitro system of cartilage slices from calf ribs whose chondroitin sulfate peptide pool consists of (A) less than 1% of very short under sulfated side chains of less than 10 disaccharide units length, (B) 3--5% of short under sulfated longer side chains (16 to 25 disaccharide units), (C) 3--5% of short, slightly oversulfated side chains (16--23 dissacharide units, very probably containing some dermatan sulfate), (D) the bulk material (74--82% of total uronate) of longest, slightly undersulfated or equally sulfated side chains (22--42 disaccharide units). After 10 min incubation rapid chain elongation with [3H]glucosamine and prelabeling with 35SO24- of endogenous acceptors are apparent. Chains of type A exhibit highest specific radioactivities. During 30--60 min incubation it is mainly chains of type B that show highest specific radioactivities, after 90 min chains of type C. On the after hand, chains of type D always incorporated the highest total amount of both precursors. Preincubation of slices for 40 min at 37 degres C strongly enhances labeling rates of all types A and B. After 10 min preincubation followed by 35SO24- labeling for 60 min, a decrease of radioactivity of type A and a distinct increase with type B are observed during the post incubation period. After pulse chase experiments type B exhibits highest specific radioactivities. The data make it evident that undersulfated short chondroitin sulfate side chains form very rapidly in a well organised manner and grow, by elongation and proceeding sulfation processes, to longer higher sulfated chains. The labeling of the hyaluronate pool is about half of that of the chondroitin sulfate pool after a lag phase of 10 min. The latter increases linearly after 35--45 min incubation time. However, after preincubation and chase experiments the hyaluronate pool is more highly labeled. The data indicate different precursor pools of both biosynthesis mechanisms, probably located in different cell compartments and/or different cartilage cells.

Animals↗
PubMed1978

Heterogeneity of rat rib chondroitin sulfate and susceptibility to rat gastric chondrosulfatase.

Cartilage chondroitin sulfate isolated directly from rat rib or from in vitro culture of rat rib constitutes a population of glycosaminoglycans which is heterogeneous with respect to size, degree of sulfation and content of N-acetyl-galactosamine 4-sulfate. Fractions, elute from Dowex-1 in order of increasing molecular size and degree of sulfation up to a certain limit. Unsulfated disaccharides and disulfated disaccharides are present in both the undersulfated chondroitin sulfate fractions and in the average or more representative chondroitin sulfate. A small content of disccharide 6-sulfate is present in all fractions and appears to be an integral part of the chondroitin 4-sulfate molecules. Rat gastric chondrosulfatase hydrolyzes sulfate preferentially from the larger chondroitin 4-sulfate molecules, and the sulfate is removed primarily from the disaccharide 4-sulfate units.

Animals↗
PubMed1981

The metabolic fate of 14C-labeled immunoadjuvant peptidoglycan monomer. II. In vitro studies.

Peptidoglycan monomer (GlcNAc-MurNAc-L-Ala-D-isoglutamine-meso-diaminopimelic acid-D-Ala-D-Ala), labeled with 14C both in the disaccharide and pentapeptide portions, was incubated with slices of mouse liver, kidney or spleen as well as with mouse and human blood, blood cells plasma and serum. Peptidoglycan monomer was isolated unchanged after incubations with mouse organs and blood cells. However, upon incubation with mouse or human blood, 10-50% of the peptidoglycan monomer underwent hydrolysis to the corresponding disaccharide and pentapeptide. After incubations with plasma and serum more than 90% of the [14C]peptidoglycan monomer was metabolized: about 50% of the administered radioactive dose was recovered in the disaccharide unit and about 35% in the pentapeptide part. These results suggest that in blood, plasma and serum of mouse and man, an N-acetylmuramoyl-L-alanine amidase (mucopeptide amidohydrolase, EC 3.5.1.28) exists which splits the amide bond between the lactyl carboxyl group of the muramyl residue and the amino group of the peptide moiety in the peptidoglycan molecule.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1984

Heterogeneity of cell-associated and secretory heparan sulphate proteoglycans produced by cultured human neuroblastoma cells.

Biosynthetically radiolabelled heparan sulphate proteoglycans have been isolated from the growth medium and the cell lysate of a human neuroblastoma cell line (CHP100). Chromatography on Sepharose CL-4B identified two heparan sulphate proteoglycans in the medium (Kav 0.220 and 0.389), whereas in the cell lysate the major proteoglycan species were more heterogenous and of a smaller overall molecular size (Kav 0.407) than the medium-derived counterparts. Chromatography on Sepharose CL-6B of free heparan sulphate glycosaminoglycan chains showed that the majority of cell-layer-derived material heparan sulphate 2, Kav = 0.509) was smaller than medium heparan sulphates (heparan sulphate 1 and heparan sulphate 2, Kav 0.230 and 0.317). Analysis of the patterns of polymer sulphation by nitrous acid treatment, gel chromatography and high-voltage electrophoresis established that in each heparan sulphate fraction there was on average 1.1 sulphate residues per disaccharide with an N:O sulphate ratio of 1.1. Heparan sulphate in the medium had a high proportion of di-O-sulphated disaccharides in regions of the chain with repeat disaccharide sequences of structure GlcA-GlcNSO3, whereas cell-associated material was enriched in di-O-sulphated tetrasaccharides of alternating sequences GlcA-GlcNAc-GlcA-GlcNSO3. The identification of several populations of heparan sulphate proteoglycans differing in molecular size and glycosaminoglycan fine structure may reflect the functional diversity of this family of macromolecules in the nervous system.

Cell Line↗