scholarly journals Studies on the carbohydrate moiety of α1-acid glycoprotein (orosomucoid) by using alkaline hydrolysis and deamination by nitrous acid

1971 ◽  
Vol 124 (3) ◽  
pp. 591-604 ◽  
Author(s):  
M. Isemura ◽  
K. Schmid

Alkaline hydrolysis followed by deamination with nitrous acid was applied for the first time to a glycoprotein, human plasma α1-acid glycoprotein (orosomucoid). This procedure, which specifically cleaves the glycosaminidic bonds, yielded well-defined oligosaccharides. The trisaccharides, which were obtained from the native protein, consisted of a sialic acid derivative, galactose and 2,5-anhydromannose. The linkage between galactose and 2,5-anhydromannose is most probably a (1→4)-glycosidic bond. A hitherto unknown linkage between N-acetylneuraminic acid and galactose was also established, namely a (2→2)-linkage. The three linkages between sialic acid and galactose described in this paper appear to be about equally resistant to mild acid hydrolysis. The disaccharide that was derived from the desialized glycoprotein consisted of galactose and 2,5-anhydromannose. Evidence was obtained for the presence of a new terminal sialyl→N-acetylglucosamine disaccharide accounting for approximately 1mol/mol of protein. The presence of this disaccharide may explain the relatively severe requirements for the complete acid hydrolysis of the sialyl residues. The present study indicates that alkaline hydrolysis followed by nitrous acid deamination in conjunction with gas–liquid chromatography will afford relatively rapid determination of the partial structure of the complex carbohydrate moiety of glycoproteins.

1971 ◽  
Vol 49 (7) ◽  
pp. 829-837 ◽  
Author(s):  
Roger L. Hudgin ◽  
Harry Schachter

The properties of CMP-N acetylneuraminic acid: glycoprotein sialyltransferase have been studied in pork serum, a crude pork liver homogenate, and a soluble acetone powder extract prepared from pork liver. Whereas the crude liver homogenate enzyme is activated by the detergent Triton X-100, this detergent has no effect on the activities of either serum or acetone powder extract; since high-speed centrifugation does not sediment the enzyme activities of the latter two preparations, it is concluded that they are soluble. Comparison of the membrane-bound and soluble liver enzymes indicates that the membrane modifies kinetic behavior only to a limited extent. In both liver and serum, a single sialyltransferase is responsible for incorporation of sialic acid into α1-acid glycoprotein, fetuin, and N-acetyllactosamine, and sialic acid incorporation occurs whenever a terminal galactose linked (β, 1 → 4) to a penultimate N-acetylglucosamine is presented to the enzyme. Although the serum enzyme resembles the liver enzyme, both the source and function of serum sialyltransferase are unknown.


1973 ◽  
Vol 133 (4) ◽  
pp. 623-628 ◽  
Author(s):  
A. Neuberger ◽  
Wendy A. Ratcliffe

The hydrolysis of the model compound 2-O-methyl-4,7,8,9-tetra-O-acetyl-N-acetyl-α-d-neuraminic acid and neuraminidase (Vibrio cholerae) closely resembled that of the O-acetylated sialic acid residues of rabbit Tamm–Horsfall glycoprotein. This confirmed that O-acetylation was responsible for the unusually slow rate of acid hydrolysis of O-acetylated sialic acid residues observed in rabbit Tamm–Horsfall glycoprotein and their resistance to hydrolysis by neuraminidase. The first-order rate constant of hydrolysis of 2-methyl-N-acetyl-α-d-neuraminic acid by 0.05m-H2SO4 was 56-fold greater than that of 2-O-methyl-4,7,8,9-tetra-O-acetyl-N-acetyl -α-d-neuraminic acid. Kinetic studies have shown that in the pH range 1.00–3.30, the observed rate of hydrolysis of 2-methyl-N-acetyl-α-d-neuraminic acid can be attributed to acid-catalysed hydrolysis of the negatively charged CO2− form of the methyl ketoside.


1974 ◽  
Vol 60 (3) ◽  
pp. 764-773 ◽  
Author(s):  
Douglas M. Gersten ◽  
Thomas W. Kimmerer ◽  
H. Bruce Bosmann

Normal rat liver lysosomes were isolated by the technique of loading with Triton WR-1339. Purity of the preparation was monitored with marker enzymes; a high enrichment in acid hydrolases was obtained in the tritosome fraction. In 0.0145 M NaCl, 4.5% sorbitol, 0.6 mM NaHCO3, pH 7.2 at 25°C the tritosomes had an electrophoretic mobility of -1.77 ± 0.02 µm/s/V/cm, a zeta potential of 23.2 mV, a surface charge of 1970 esu/cm2, and 33,000 electrons per particle surface assuming a tritosome diameter of 5 x 10-7 m. Treatment of the tritosomes with 50 µg neuraminidase/mg tritosome protein lowered the electrophoretic mobility of the tritosome to -1.23 ± 0.02 µm/s/V/cm under the same conditions and caused the release of 2.01 µg sialic acid/mg tritosome protein. Treatment of the tritosomes with hyaluronidase did not affect their electrophoretic mobility, while trypsin treatment elevated the net negative electrophoretic mobility of the tritosomes. Tritosome electrophoretic mobilities indicated a homogeneous tritosome population and varied greatly with ionic strength of the suspending media. pH vs. electrophoretic mobility curves indicated the tritosome periphery to contain an acid-dissociable group which likely represents the carboxyl group of N-acetylneuraminic acid; this was not conclusively proven, however, since the tritosomes lysed below a pH of 4 in the present system. Total tritosome carbohydrate (anthrone-positive material as glucose equivalents) was 0.19 mg/mg tritosome protein while total sialic acid was 3.8 µg (11.4 nmol)/mg tritosome protein. A tritosome "membrane" fraction was prepared by osmotic shock, homogenization, and sedimentation. Approximately 25% of the total tritosome protein was present in this fraction. Analysis by gas-liquid chromatography and amino acid analyzer showed the following carbohydrate composition of the tritosome membrane fraction (in microgram per milligram tritosome membrane protein): N-acetylneuraminic acid, 14.8 ± 3; glucosamine, 24 ± 3; galactosamine, 10 ± 2; glucose, 21 ± 2; galactose, 26 ± 2; mannose, 31 ± 5; fucose, 7 ± 1; xylose, 0; and arabinose, 0. The results indicate that the tritosome periphery is characterized by external terminal sialic acid residues and an extensive complement of glycoconjugates. Essentially all the tritosome N-acetylneuraminic acid is located in the membrane and about 53% of it is neuraminidase susceptible.


1974 ◽  
Vol 139 (2) ◽  
pp. 415-420 ◽  
Author(s):  
Michael Messer

The identity of a novel form of sialyl-lactose found in milk of the echidna (Tachyglossus aculeatus) was investigated. The sialyl-lactose yielded equimolar amounts of N-acetylneuraminic acid and lactose during mild acid hydrolysis but was resistant to the action of a bacterial neuraminidase. A viral neuraminidase hydrolysed it to lactose plus a form of sialic acid that reacted positively with thiobarbituric acid reagent but whose chromatographic mobility was greater than that of N-acetylneuraminic acid. Treatment with alkali converted the sialyl-lactose into a substance with the same chromatographic mobility as N-acetylneuraminyl-(2→3)-lactose and made it susceptible to the action of bacterial neuraminidase. The sialyl-lactose contained one mol of ester (identified as acetyl), and released one mol of formaldehyde during periodate oxidation, per mol of sialic acid. It did not contain N-glycollylneuraminic acid. These results indicate that the sialyl-lactose is N-acetyl-4-O-acetylneuraminyl-(2→3)-lactose. Echidna milk contained, in addition, a small amount of N-acetylneuraminyl-(2→3)-lactose.


1968 ◽  
Vol 106 (2) ◽  
pp. 523-529 ◽  
Author(s):  
J. Schrager ◽  
M. D. G. Oates

1. The sugars and amino sugars of hydrolysates of gastric secretion were determined by gas–liquid chromatography. 2. All the gastric aspirations examined showed on hydrolysis the presence of fucose, galactose, mannose, glucose, galactosamine, glucosamine, N-acetylneuraminic acid and sulphate. 3. Galactose and glucosamine were always found in equimolar amounts, but the galactose/galactosamine ratio in different aspirations was 2:1, 3:1, 4:1 or 5:1. Repeated gastric aspirations of each subject examined showed constant ratios of these carbohydrate components. 4. Fucose and sialic acid appear to be related to glucosamine and galactosamine respectively. 5. The carbohydrate components of extracts from the mucous glands of the body mucosa and antrum did not differ from those of gastric secretion.


1969 ◽  
Vol 115 (4) ◽  
pp. 817-822 ◽  
Author(s):  
Anatoly Bezkorovainy ◽  
Dietmar Grohlich

1. Two glycoproteins were isolated from the M-1 acid glycoprotein fraction of bovine colostrum. 2. The lighter glycoprotein had a molecular weight of 7200, contained about 28·4% of carbohydrate, and had an absorption maximum at 275nm. The heavier glycoprotein had a molecular weight of 12000, contained 39·0% of carbohydrate, and had no absorption maxima in the 240–300nm. range of the spectrum. 3. The carbohydrate moiety of both glycoproteins was removable from the polypeptide moiety under the conditions of the β-elimination reaction. 4. Periodate oxidation experiments showed that sialic acid was linked to galactose in both proteins.


2021 ◽  
Vol 28 ◽  
pp. 100777
Author(s):  
Christel Tran ◽  
Licia Turolla ◽  
Diana Ballhausen ◽  
Sandrine Cornaz Buros ◽  
Tony Teav ◽  
...  

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Hüseyin Can ◽  
Sedef Erkunt Alak ◽  
Ahmet Efe Köseoğlu ◽  
Umut Şahar ◽  
Berna Bostanbaş ◽  
...  

Abstract Background Cytidine monophospho-n-acetylneuraminic acid hydroxylase (CMAH) gene associated with blood groups in cats encodes CMAH enzyme that converts Neu5Ac to Neu5Gc. Although variations in CMAH gene of pedigree cats have been revealed, the presence/lack of them in non-pedigree stray cats is unknown. Therefore, the present study aimed to investigate the variations in CMAH gene and the quantity of Neu5Ac and Neu5Gc on erythrocytes of non-pedigree stray cats (n:12) living in İzmir, Turkey. Also, the frequency of blood types was determined in 76 stray cats including 12 cats that were used for CMAH and Neu5A/Neu5Gc analysis. Results In total, 14 SNPs were detected in 5’UTR as well as in exon 2, 4, 9, 10, 11 and 12 of CMAH gene. Among these SNPs, -495 C > T in 5’UTR was detected for the first time as heterozygous in type A and AB cats, and homozygous and heterozygous in type B cats. The remaining 13 that have been detected in previous studies were also found as homozygous or heterozygous. Both Neu5Gc and Neu5Ac were detected in type A and AB cats. In type B cats, only Neu5Ac was detected. Among two type AB cats, the level of Neu5Ac was found higher in cat carrying heterozygous form (T/C) of 1392T > C. The prevalence of type B cats (67.1 %) was higher than others. Conclusions The presence of a new SNP as well as previous SNPs indicates that more variations can be found in stray cats with a more comprehensive study in the future. Also, the high prevalence of type B cats demonstrates the possible risk of neonatal isoerythrolysis among stray cats living in İzmir, Turkey.


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