Characterization of alpha-L-rhamnosidase of Bacillus sp. GL1 responsible for the complete depolymerization of gellan.
A bacterium, Bacillus sp. GL1, depolymerizes a heteropolysaccharide (gellan) to a tetrasaccharide (unsaturated glucuronyl-glucosyl-rhamnosyl-glucose) by extracellular gellan lyase. The resultant tetrasaccharide was degraded to the constituent monosaccharides by subsequent reactions of unsaturated glucuronyl hydrolase, beta-d-glucosidase, and alpha-l-rhamnosidase. alpha-l-Rhamnosidase was substantially induced in the bacterial cells when grown in a medium containing gellan as a carbon source. The purified enzyme from the cells was a monomer with a molecular mass of about 100 kDa and was most active at pH 7.0 and 50 degrees C. The enzyme acted on the gellan-degrading product (rhamnosyl-glucose) formed after successive reactions catalyzed by gellan lyase, unsaturated-glucuronyl hydrolase and beta-d-glucosidase, and released rhamnose from the disaccharide. Therefore, the alpha-l-rhamnosidase is found to be responsible as the final enzyme for the complete depolymerization of gellan.
Hashimoto
W
W
Research Institute for Food Science, Kyoto University, Uji, 611-0011, Japan.
Nankai
H
H
Sato
N
N
Kawai
S
S
Murata
K
K
D001407:Bacillus / Q000201:enzymology*; D002240:Carbohydrate Sequence; D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D013696:Temperature
D009844:Oligosaccharides; D011135:Polysaccharides, Bacterial; C048288:gellan gum; D006026:Glycoside Hydrolases; C022525:alpha-L-rhamnosidase