A- -Glucan

Pustulan (a glucan from the lichen Umbilicaria pustulata)... 

It may be that this fact was associated with the rather complex composition of fungal mycelium, consisting of chitin enclosed in a glucan matrix (Bowman, Free, 2006). Therefore, mature saprophyte mycelium are completely covered by difficult-soluble glucans and the fraction of chitin in the apical cell wall is not sufficient. As such, we supposed that these cationic isoforms bound with another major component of the fungi... 

Several methylated sugars have been identified in hydrolyzates of LPS, cell-wall polysaccharides, and extracellular polysaccharides. A considerable number of these have been found in the LPS from photosynthetic prokaryotes. Two polysaccharides from Mycobacterium species, a glucan" and a mannan" are remarkable in that they contain high percentages of methylated sugars. Glycolipids from Mycobacterium species are also rich in methylated sugars, some of which have not been found elsewhere, but this is beyond the scope of the present article. 

Tocotrienols are another group of phytochemicals of rice bran which have a chemopreventive effect and have been demonstrated to inhibit breast cancer (Nesaremam et al., 1998). The polysaccharides of rice bran contain a-glucan, the anti-tumor effect of which has been demonstrated by its inhibition of gastrointestinal carcinogenesis (Akeshita et al., 1992). Rice bran agglutinin has been shown to induce apoptosis of cancer cells by the mechanism of cell cycle dysregulation (Miyoshi et al., 2001). 

T. Pijning, A. Vuijicic-Zagar, S. Kralj, W. Eeuwema, L. Dijkhuizen, and B. W. Dijkstra, Biochemical and crystallographic characterization of a glucan-sucrase from Lactobacillus reuteri 180, Biocatal. Biotransformation, 26 (2008) 12-17. 

L. K. Skov, O. Mirza, A. Henriksen, G. P. De Montalk, M. Remaud-Simeon, P. Sarcabal, R. M. Willemot, P. Monsan, and M. Gajhede, Amylosucrase, a glucan-synthesizing enzyme from the alpha-amylase family, J. Biol. Chem., 276 (2001) 25273-25278. 

This enzyme [EC 2.4.1.4], also referred to as sucrose-glucan glucosyltransferase, catalyzes the reaction of sucrose with a glucan (specifically, [(l,4)-o -D-glucosyl] ) to yield D-fructose and a longer glucan (that is, [(l,4)-o -D-glucosyl] +i). 

Starch granules are composed of two types of a-glucan, amylose and amylopectin, which represent approximately 98-99% of the dry weight. The ratio of the two polysaccharides varies according to the botanical origin of the starch. 

The molecular-weight distribution of a sample of a glucan, pul-lulan, isolated from cultures of the fungus Pullularia pullulans grown in sucrose solutions,"6 was determined by Granath and Kvist69 by the method developed by these workers for use with dextrans. Here, too, the column was calibrated with dextran fractions, as the shape of the pullulan molecule was believed to be sufficiently similar to that of a dextran to permit use of the same correlation of Kav with molecular weight for both polysaccharides. 

Shimizu, N., S. Ohtsu, M. Tomoda, R. Gonda, and N. Ohara. 1994. A glucan with immunological activities from the tuber of Alisma orientate. Biol. Pharm. Bull. 17 1666-1668. 

Table 4.6.14 Enzyme activities (1,4-a-glucan branching enzyme) in liver, muscle, and fibroblasts... 

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