THE CARBOHYDRATE-POLYPEPTIDE LINKAGES, THE AMINO ACID SEQUENCES OF THE PEPTIDES ADJACENT TO SOME OF THESE BONDS, AND THE COMPOSITION AND SIZE OF THE CARBOHYDRATE UNITS OF ALPHA-1-ACID GLYCOPROTEIN

Study of exopolysaccharide produced by Streptomyces rochie strain OF1 and its effect as ameliorative on osteoarthritis in rats via inhibiting TNF-α/COX2 pathway

BACKGROUND

Carbohydrates are known as the main natural products of life activities.

RESULTS

Streptomyces rochie strain OF1 isolated from a mangrove tree produced exopolysaccharide S5 (EPSS5) (14.2 gl^-1) containing uronic acid 21.98% sulfate content of 11.65 mg/ml, and a viscosity of 1.35 mm²/s. while total hexose amine content was 24.72%. The high performance liquid chromatography (HPLC) analysis of mono sugars revealed that EPS was composed of manouronic acid, glucuronic acid, xylose, and fructose at a molar ratio of 1.0:0.5:1.0:2.0, respectively. It showed that the whole antioxidant activity was 92.06%. It showed antibacterial activity against Staphylococcus aureus, and E. coli, MRSA and Klebsiella pneumoniae. But, EPSS5 displayed low antifungal activity against Candida albicans. While no antifungal activity has been detected against Aspergillus niger. EPSS5 has antibiofilm action that is noticeable toward S. aureus with an inhibition ratio of biofilm up to 50%. Effect of EPS on serum levels of TNF-α and COX2 by 2 fold and 1.9 fold of EPS reduced serum levels of Tumor necrosis factor-α (TNF-α) by 38%, 12%, 49%, and Cyclooxygenase-2 (COX2) by 61%, 34%, and 62%, respectively. By affected of EPSS5 on arthritis in rats stimulated by carrageenan.

CONCLUSIONS

Administration of EPS ameliorated carrageen-induced elevation in inflammatory mediators; TNF-α/COX and suppressed the expressions of metalloproteinase 9 (MMP9) by 68%, 86%, and 75% correspondingly in comparison to the group of carrageenans. Then again, therapy involving a high dose only reduced MMP9 level by 57%, compared to free drug suggesting that EPSS5 is a good inhibitor of the MMP9, as it brought MMP9 back to normal levels via the signaling pathway.

endo-beta-N-acetylglucosaminidase F: endoglycosidase from Flavobacterium meningosepticum that cleaves both high-mannose and complex glycoproteins

We have detected an endoglycosidase activity produced by Flavobacterium meningosepticum. This enzyme, named endo F, cleaves glycans of both the high-mannose and the complex type linked through asparagine to the protein backbone. The data indicate that cleavage occurs via hydrolysis of the glycosidic bond of the N,N'-diacetylchitobiose core structure adjacent to asparagine, similar to that due to endo H and endo D. Extreme variability was noted in the availability of this cleavage site among N-linked glycoproteins. Glycoproteins of retrovirus, lymphocytic choriomeningitis virus, Pichinde virus, and HLA-A and -B antigens were readily cleaved in the presence of nonionic detergent. Others, such as ovalbumin, fetuin, bromelain, ovomucoid, alpha 1-acid glycoprotein, immunoglobulin G, and influenza virus hemagglutinin became susceptible only after reduction and alkylation or when cleavage was performed in the presence of 1% 2-mercaptoethanol. Endo F should prove useful in the study of glycans and protein backbones as discrete entities and for defining the nature of the glycan-protein interface.

The periodate oxidation of bovine bone sialoprotein, and some observations on its structure

1. Bovine bone sialoprotein (mol.wt. 23000) contains N-acetylneuraminic acid and N-glycollylneuraminic acid, fucose, galactose, mannose, N-acetylgalactosamine and N-acetylglucosamine residues in the form of a very small number, perhaps one, of highly branched oligosaccharide structures linked covalently to peptide. 2. Periodate oxidation of the sialoprotein results in quantitative destruction only of the sialic acid and fucose residue consistent with the earlier findings of their positions as terminal groups. 3. Terminal sialic acid residues are attached to galactopyranose residues by 2,3-linkages, and to some N-acetylgalactosamine residues (at C-6). 4. Sequential Smith degradation indicates that N-acetylgalactosamine residues may be present as points of branching (linked in C-1, C-3 and C-6) and N-acetylglucosamine residues are located in the inner part of the structure, adjacent to the carbohydrate-peptide bond(s). 5. Mannose residues appear to be linked in the 1,3-positions.

Reduction and alkylation of human plasma orosomucoid in aqueous solution and in 8 M urea: a physicochemical and immunochemical study. Human orosomucoid: reduction and alkylation

Highly purified orosomucoid (α1-acid glycoprotein) was exposed to mercaptoethanol, iodoacetamide and 8 M urea, in various combinations. The derivatives were examined by agar-gel electrophoresis, by acrylamide-gel "disc" electrophoresis (employing an improved method), by immunodiffusion techniques, and by quantitative immunochemical methods.The results indicated an —S—S— dependent tertiary structure for the polypeptide backbone, but one which could not be separated into subunits by the methods employed. The mechanisms of reduction and alkylation of the glycoprotein are discussed, and several alternate structural models for the polypeptide moiety are presented.

Partial characterization of the sialic acid-free forms of alpha-1-acid glycoprotein from human plasma

Some of the properties of sialic acid-free alpha(1)-acid glycoprotein prepared by mild acid hydrolysis (pH1.6 at 80 degrees for 1hr.) were compared with those of neuraminidasetreated alpha(1)-acid glycoprotein. Chemically, the former contained less fucose (15%) and amide (2%) residues. Physicochemically, it had undergone certain changes primarily pertaining to the secondary structure, so that the specific optical rotation was more negative than that of the latter. A further expression of this change is probably the difference in the pH range of the resolution into two bands on electrophoresis. The resolution of the glycoprotein prepared by mild acid hydrolysis seems to be extended to more acidic pH values both by starch-gel and free moving-boundary electrophoresis. On ultracentrifugation both preparations appeared homogeneous and sedimented with a rate of 3s. Removal of sialyl residues at different pH values, in the range 1-7, showed that 2moles of sialic acid/mole of protein are very strongly bound. The two variants of alpha(1)-acid glycoprotein were isolated from pooled sialic acid-free alpha(1)-acid glycoprotein by preparative starch-gel electrophoresis and from selected blood of normal adults by fractionation by solubility and chromatography. Ultracentrifugal and starch-gel electrophoretic analyses at pH5, with incubation times of 1 or 24hr., demonstrated that no dissociation-association equilibrium (constant sedimentation coefficient and molecular weight) or isomerization (constant apparent electrophoretic mobilities) exist between the two variants. Therefore these variants are not sub-units of native alpha(1)-acid glycoprotein but represent modifications of naturally occurring proteins. Further, it was shown that the difference in the electrophoretic mobilities between the two variants was not due to any difference in amide content. Immunochemically, the two variants share the same determinants.