Linkage sequence

The same linkage sequence has been recently described for the O-polysaccharide of the lipopolysaccharide of Lanyl strain 0 7a,b of Pseudomonas aeruginosa this strain is possibly identical to Fisher type 2 (20). 

Regiocontrol in the insertion sequence appears to be steric in origin, with laige groups directed away from the bulky metal. A tail-to-tail linkage sequence followed by rearrangement leads to l,3,S-tris(t-butyl)benzene as the sole benzenoid product from trimerization of r-butylacetylene in the presence of PdCb. 

Two Disaccharides from Carboxyl-Reduced Heparin. The Linkage Sequence in Heparin, M. L. Wolfrom. J. R. Vercellotti, and D. Horton,/. Org. Chem., 29,540-547... 

Wolfrom ML, Vercellotti JR, Horton D. Two disaccharides from carboxyl-reduced heparin. Linkage sequence in heparin. J Org Chem 1964 29 540-547. 

The structure (j) is of great important as the linkage sequence between many glycosaminoglycan chains and protein (see below). 

The assembly of the linkage sequences has been studied in some detail in cell-free systems. Both transferases are membrane-bound in a wide variety of tissues and sediment with the microsomal fraction, from which they can be made soluble with detergents. 

For some polysaccharides, such as keratan sulphate, the linkage sequences seem to have the same sfructixres as the oligosaccharides of conventional glycoproteins and the pathways of their synthesis are presumably the same. Hence mucin-type or complex-type chains can act as link sequences and so dolichol can be involved in some forms of link production. Some other polysaccharides, such as heparin, are attached to sequences that have no known counterpart in typical glycoprotein assembly. 

The assembly of the linkage sequence requires the orderly, sequential action of four enzymes, a xylosyltransferase, two different galactosyl-transferases and a glucuronosyltransferase. To var3dng extents, each of these has been partially purified and characterised, especially with regard to specificity. Essentially, each shows a specificity for the product of the enzyme which precedes it in the sequence of assembly, but the enzymes differ, nevertheless, in the narrowness of their acceptor specificities. 

Barley and oats P-Glucan glucose P-1,4 linked spine with P-1,3 side linkages sequence of linkages varies between barley and oats and between cultivars p-glucanase... 

A j8-D-glucanase highly specific for jS-D-glucans containing a linkage sequence (13) has been isolated from several commercial preparations of Bacillus subtilis a-amylase including one purified by repeated crystallization. The... 

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