Rihei Takahashi

Structural investigation of a galactoglucomannan from cell walls of tobacco (Nicotiana tabacum) midrib

Abstract Cell-wall polysaccharides of the midrib of Nicotiana tabacum were fractionated into pectin, hemicellulose, and α-cellulose components. From the α-cellulose fraction, a polymer composed of d -galactose, d -glucose, and d -mannose in the molar ratios ∼1:2:4 was extracted by aqueous 25% sodium hydroxide-5% boric acid and purified by barium hydroxide precipitation, ion-exchange chromatography, and gel filtration. Methylation analysis, enzymic degradation, and 13 C-n.m.r. studies showed that the polysaccharide was built up of (1→4)-linked β- d -glucopyranosyl and β- d -mannopyranosyl residues in the molar ratio ∼1:2, and that ∼14% of the d -mannosyl residues were substituted at O-6 by α- d -galactopyranosyl or 2- O -β- d -galactopyranosyl-α- d -galactopyranosyl side-chains.

Enzymatic preparation of β-1,4-mannooligosaccharides and β-1,4-glucomannooligosaccharides

Publisher Summary Mannooligosaccharides have been prepared from partial acid and enzymatic hydrolysates of plant mannans such as ivory nut, guaran, coffee bean, white spruce, and lucerne seeds. This ordinary preparation method, however, does not yield a substantial quantity of oligosaccharides. The chapter describes preparation method for mannooligosaccharides from copra mannan using the mannanase system from Streptomyces sp. The mannanase of Streptomyces has been observed to rapidly decrease the viscosity of viscous polysaccharides such as konjac glucomannan, guar gum, and locust bean galactoglucomannans. The enzyme is a typical endoenzyme. Therefore, the products arising from the enzymatic degradation of the substrate are heterooligosaccharides, that is, various glucomanno- or galactomannooligosaccharides. The chapter also describes the preparation of glucomannooligosaccharides from konjac glucomannan.

β-Mannanase of Streptomyces

Publisher Summary β-Mannanase refers to hydrolytic enzymes capable of hydrolyzing the (1→4)-β-D-mannopyranosyl linkages of the (1→4)-β-D-mannans, namely, mannan, galactomannan, glucomannan, and galactoglucomannan. The enzymes have been reported to be produced by various microorganisms including bacteria, fungi, and Streptomyces, and to occur in animals and plants. This chapter describes the isolation of mannanase-producing Streptomyces. The chapter describes the purification procedure and some properties of the enzyme. Copra mannan was used as a substrate for the determination of mannanase activity. Streptomyces sp. No. 17 as a representative strain was used in the production of mannanase because the strain showed high stability for the enzyme productivity.