Mannan-degrading enzymes

There is no information so far available about mannan degrading enzymes of alkaliphiles. In this paper, a P-mannan degrading alkaliphile Bacillus sp. AM-001) with high productivities of cell-associated P-mannosidase and three extracellular P-... 

The most characterised D-mannan degrading enzymes are the endo- -mannanases (5). These enzymes act on a range of 1,4-p-D-mannan-type polysaccharides including D-mannan, glucomannans (acetylated and deacetylated), galactomannans and galacto-glucomannans. The extent and... 

The action of /3-D-mannosidase finally degrades the D-manno-oligo-saccharides, to afford free D-mannose molecules details of this process were given in an earlier article.12 An enzyme identified as oligo-/J-D-mannosyl-(l- 4)-phosphorylase719 may also take part in the mobilization of D-galactomannan in seeds. This enzyme, in the presence of orthophosphate, acts on D-manno-oligosaccharides (obtained from partial hydrolysis of D-mannan), and yields /3-D-mannosyl phosphate. 

The properties of the enzymes used in this study have been described in former publications (10,11,15). Important for the following interpretation are their hydrolytic specificities. The xylanase did not hydrolyze either isolated mannans or celluloses—or only to a very small extent (10). The same is true for the mannanase with respect to xylans and celluloses (11,15). The avicelases, which were not purified to the same extent as the xylanase and mannanase, did not hydrolyze mannans, but they degraded xylans besides crystalline cellulose (10). Also, the highly purified cellobiohydrolase C (12) degraded xylan to some extent (Dr. E. K. Gum, Jr., personal communication). 

The three cellulases decomposed about 25-45% of the cellulose accompanied by solubilization of about 40-70% of the mannan and, by partial hydrolysis, of about 20% of the xylan present in the untreated sprucewood holocellulose. Based on the degradation products (cf. Table III, Columns 13-15, and Table II), the catalytic actions of the three cellulases—all isolated from Trichoderma viride—are similar or identical. The lower absolute degradation values obtained with cellobiohydrolase C might merely be a result of enzyme concentration. 

Oligosaccharide Degradation Products Arising from Enzymic Hydrolysis of Galacto- and Gluco-mannans... 

Methylation analysis and enzymic degradation studies established the presence of a structure (23) containing short side-chains of (1 -> 2)-at-D-mannosyl residues attached to a main backbone of (1 6)-ot-D-mannopyranosyl residues. In addition, a serologically inactive a-D-mannan whose structure (24) resembles that of the core L-arabino-D-mannan has been isolated. 

---