Mannans fungal

It is noteworthy that most of the chemical shift values for all three polymers may be closely approximated ( ) by calculations based on data for monomeric reference compounds. These findings illustrate, therefore, the general validity of studies on low molecular weight model compounds for einalysis of spectra of carbohydrate polymers. Many examples of equally satisfactory comparisons of this kind are to be found in studies on other polysaccharides (11,23). These polymers include glucans (l6), mannans (2k, 2 ), limit dextrins (26), lichenin (2j), agarose (28) and various polysaccharides of fungal and microbial orgins (e.g., 7,8,29-31). Observed departures from expectation have been attributed to specific conformational influences ( 8). 

Another biochemical topic, the biochemistry of plant galacto-mannans, is discussed by Dey (Egham, Surrey) the article rounds out aspects of the field that are complementary to those treated by Gorin and Spencer in Volume 23 (on fungal polysaccharides) and Dea and Morrison in Volume 31 (on the chemistry and interactions of seed galactomannans). 

Phosphonomannans, fungal, 394,417 Phosphorus, in yeast mannan, 391 Phosphorylases active sites of, 346 amino acids of, 345 kinetics, 289,353 mechanism of action of, 356 properties of, 347... 

Fungal polysaccharides include homopolysaccharides as well as heteropolysaccharides including D-galacto-D-mannans, D-xylo-D-mannans, etc. Scleroglucan is used as an industrial gum. Several homopolysaccharides found in fungi are shown in Table 7.11.1. 

Work on glucan and mannan structures is described in Refs. 105-108a. Taylor and Cameron109 have reviewed the preparation and quantitative analysis of fungal cell-walls. 

Degradation Products Arising from the Action of D-Mannanases of Different Fungal Origins on Various D-Mannans... 

Many other fungal mannans are heteropolymers based on an a-mannan chain [84, 55]. a-L-Rhamno-a-mannans with L-Rha al—>3, L-Rha al-2-L-Rha al—>3 and L-Rhal-4GlcAp 1 -2-L-Rhaa 1 —>3 side chains have been described. a-Gluco-a-mannans with single Glc residues attached to the mannan chain have been isolated from Ceratocystis spp. The capsular polysaccharides of the serotype of an encapsulated pathogenic yeast, Cryptococcus neoformans, have a main chain of a(l-3)... 

Lower animals, plants and fungi are dealt with in the latter parts of the chapter by comparison with the better understood systems of higher animals. With the exception of the mannan of fungal walls, the syntheses of high polymers are discussed in the next chapter. 

Fungal mannans, such as that of Saccharomyces cerevisiae contain occasional phosphate residues which are present as diesters, linking two sugar residues (see Chapter 4). In Hansenula spp. this structure is frequent, so that phosphate diester links can occur every two or three mannosyl residues in some parts of the mannan. They are attached to C-1 and C-6 of mannosyl residues which are otherwise al,2-linked, so there is close resemblance to other, less phosphorylated, fungal mannans. 

In general, the mannans and glucans of fungal walls probably arise largely in the Golgi apparatus and reach the plasmalemma in vesicles, while the chitin and cellulose at least become ordered at the plasmalemma. The real site of their biosynthesis is unclear, but they are likely to be initiated in the endomembranes (especially the RER) of the cell, with polymer assembly... 

---