Keiji Kainuma

Purification and some properties of Bacillus macerans cycloamylose (cyclodextrin) glucanotransferase

Bacillus macerans cycloamylose (cyclodextrin) glucanotransferase (EC 2.4.1.19) was purified by the technique of starch adsorption and DEAE-cellulose column chromatography, and then crystallized from an ammonium sulfate solution containing mM calcium chloride. The crystals of the enzyme were rod-shaped and showed a single band by disc-gel electrophorsis. The purified enzyme was dissociated into two subunits by sodium dodecyl sulfate-disc electrophoresis. The subunits had no enzyme activity. Details of each purification step and some properties of the enzyme are described in this paper.

Isolation and action pattern of maltohexaose producing amylase from Aerobacter aerogenes

During studies on the fine structure of amylopectin and N~igeli amylodextrin [1 ], we discovered that an unusual hydrolase activity was contained in a puUulanese preparation obtained from Aerobacter aerogenes by the method of Wallenfels et al. [2]. This hydrolase produced large amounts ofmaltohexaose (G6) from amylose, amylopectin and whole starch. Using crude enzyme extract, we could easily get more than 35% of G 6 from amylopectin. After examining more than 30 strains of Aerobacter aerogenes and cloacae, both of which organisms had the G6-producing activity, we obtained one strain of A. aerogenes which had strong and stable enzyme activity. The enzyme was separated completely from other starch-hydrolyzing activity by ammonium sulfate precipitation and DEAE-cellulose column chromatography. We report here the experimental data and evidence which support an exo action pattern of the new enzyme, analogous to that of t3-amylase and Pseudomonas stutzeri amylase, the latter as reported by Robyt et al. [3].

Control of starch and exocellular polysaccharides biosynthesis by gibberellic acid with cells of sweet potato cultured in vitro.

The regulation of starch synthesis and exocellular polysaccharide synthesis by GA3 was studied with cells of sweet potato grown as suspension in glycerol medium. In the presence of GA3, and under normal cell growth, starch formation was inhibited. The incorporation activity (starch synthesis) from ADP-[14C] glucose or UDP-[14C] glucose with GA3 treated cells was reduced. On the other hand, the synthesis of exocellular polysaccharides composed of glucose, galactose, mannose and arabinose etc., was stimulated and a clear increase of the Man/Ara ratio was observed in the presence of GA3. These results may indicate that GA3 affects the regulation of starch synthesis and exocellular polysaccharide synthesis.

Bioconversion of cellulose to α-1,4-glucan

SummaryA biochemical procedure to convert β-1,4-glucosepolymer (cellulose) to α-1,4-glucosepolymer (starch) has been studied in vitro. Cellulose was hydrolyzed to cellobiose by cellobiose producing cellulase which was isolated from culture filtrates of Cellvibrio gilvus. A 90% hydrolysation was obtained after 12 h at 37 °C. The product was found to contain only cellobiose when examined paperchromato-graphically. The second step was the conversion of cellobiose to glucose 1-phosphate by cellobiose phosphorylase, purified from extracts of C. gilvus. After incubation for 1 h at 37 °C, the percentage conversion of cellobiose into glucose 1-phosphate was approx. 20%. The third step, the bioconversion of glucose 1-phosphate to α-glucose polymer, was carried out by α-glucan phosphory lase, incubated with primer at 37 °C for 24 h; about 55% conversion was obtained. The products formed white precipitates, gave a blue colour on treatment with iodine and were hydrolyzed by glucoamylase. This result shows that approx. 10% of cellulose could be converted to α-1.4-glucan, could be converted to α-1.4-glucan, such as amylose, via glucose 1-phosphate.