Sulphate Lyases AC

The chondroitin sulphate lyase AC (mol. wt. 7.5—8.0 x 10 ) from Arthrobacter aurescens is a glycoprotein containing residues of D-mannose, D-glucose, 2-amino-2-deoxy-D-glucose, and D-glucuronic acid (molar proportions 3 5 4 2). The amounts of a-helix and -structure present in the protein chain were estimated to be 16 and 25 %, respectively, by o.r.d. and c.d. spectroscopy, etc. 

New sensitive assays for dextranase activity are based on the use of Sephadex substituted with either 2,4,6-trinitrophenyl groups (for spectrophotometric assay) or fluorescamine groups (for fluorometric assay). 3,5-Dinitrosalicylic acid has been used in automated assays to determine the reducing sugars released on hydrolysis of the appropriate substrates with soluble or insoluble dextranases and other polysaccharide hydrolases.  

A dextran-dextranase system has been used to examine the synergistic effect of exo- and cndo-enzymes acting jointly on polymeric substrates. An endo-dextranase (from Penicillium funiculosum) and an cxo-dextranase (from Streptococcus mitis) produced D-glucose more rapidly from dextrans than the summed effects of the individual enzymes. 

The prevention of dental caries in rats by a dextranase from a strain of Spiearia violacea has been studied.  

Active immobilized derivatives of dextranase have been obtained by chelation with hydrous zirconium(iv) oxide and porous titanium(iv) oxide.  

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An improved method for the microdetermination of glycosaminoglycuronans after digestion with chondroitin sulphate lyase ABC and chondroitin sulphate lyase AC has been reported. However, it is based on the already reported... 

Arthrobacter aurescens secretes an enzyme that hydrolyses chondroitin sulphate. The enzyme crystallized after purification and exhibited the following properties pH optimum 6.0, temperature optimum 50 C, and pH stability 4.9—7.4 it was stable below 45 °C and hydrolysed chondroitin 4- and 6-sulphates, chondroitin, and hyaluronic acid (ratio of initial rates 1.0 1.1 1.95 3.2). The hydrolyses of chondroitin 4- and 6-sulphates furnished 2-acetamido-2-deoxy-3-0-(4-deoxy-a-L-t/irco-hex-4-enopyranosyluronic acid)-D-galactose 4- and 6-sulphates, respectively. Since the enzyme is inactive against dermatan sulphate, it is a chondroitin sulphate lyase AC. 

An enzyme that hydrolyses dermatan sulphate, but neither chondroitin 4-sulphate nor chondroitin 6-sulphate, has been isolated from Flavobacterium heparinum grown in the presence of glycosaminoglycans. Chondroitin and dermatan sulphates and disaccharides obtained from them induced the synthesis of this enzyme, which was separated from a chondroitin sulphate lyase AC. The enzyme acted on dermatan sulphate to give an unsaturated, sulphated disaccharide and higher oligosaccharides. 

Changes in the capacity of hepatoma cells to the binding of Ricinus communis lectin have been noted after treatment with chondroitin lyase AC. The binding sites for this lectin, but not those for concanavalin A, are masked with chondroitin 4-sulphate. By use of a direct method for studying the binding... 

Glycosaminoglycans have been isolated from guinea-pig basophilic leukocytes after treatment with proteolytic enzymes. Further treatment with chondroitin lyase AC, chondroitin lyase ABC, and heparan sulphate lyase was used to identify chondroitin sulphate (55%), dermatan sulphate (30%), and heparan sulphate (15%). 

Biosynthesis. — Up to 56% of sulphated glycosaminoglycans synthesized by explant cultures of human and rabbit articular chondrocytes are located in the trypsin-digestible pericellular coat. ° Sulphate is incorporated into both D-glucopyranosyluronic acid and L-idopyranosyluronic acid residues in hybrid glycosaminoglycans by monolayers of chick embryo arterial fibroblasts. Several oligosaccharides, released on treatment with chondroitin lyase ABC and chondroitin lyase AC, have been characterized. 

A dodecasaccharide that was obtained by hydrolysis of dermatan sulphate with testicular hyaluronidase, chondroitin lyase AC, and jS-D-glucuronidase yielded a sulphated 2-amino-2-deoxy-D-galactose derivative when treated with human serum at pH 4.5 or 7.0. No further degradation of the substrate occurred, suggesting that normal human serum possesses an cxo-jS-D-acetamidodeoxyhexosidase that is active towards dermatan sulphate. 

Cerebroside-3-sulphate 3-sulphohydrolase Poly[ 1,4-p-(2-acetamido-2-deoxy-D-glucoside)] glycanohydrolase Acylcholine acyl hydrolase Chondroitin AC lyase... 

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