Improved yields of cyclic nigerosylnigerose from starch by pretreatment with a thermostable branching enzyme.
Cyclic nigerosylnigerose (CNN) is produced enzymatically from starch by the combined action of 6-alpha-glucosyltransferase and 3-alpha-isomaltosyltransferase. In our previous study, alpha-1,6-branching chains found in the structure of amylopectin and glycogen were shown to be favorable for CNN formation by the two enzymes. Therefore, we examined whether the introduction of alpha-1,6-branch points into starch using the action of branching enzyme (BE) could improve the yield of CNN from starch. Thermostable BE from Geobacillus stearothermophilus TC-91 was prepared as a purified recombinant protein. Pretreatment of amylose with BE considerably increased the CNN yield from 5% to 38%. When BE acted on tapioca starch, the CNN yield was elevated from 47% to 60%. Conversely, BE treatment of waxy corn starch containing very little amylose resulted in a negligible increase in CNN yield. In addition, BE exerted a beneficial effect when starch with a lower degree of hydrolysis was used as a substrate. The present results indicate that the addition of alpha-1,6-glucosidic linkages to starch using BE is an effective strategy to improve the yield of CNN from starch.
Aga
Hajime
H
Glycoscience Institute, Hayashibara Biochemical Laboratories, Inc., 675-1Fujisaki, Naka-ku, Okayama 702-8006, Japan.
Okamoto
Iwao
I
Taniguchi
Mituki
M
Kawashima
Akira
A
Abe
Hiroko
H
Chaen
Hiroto
H
Fukuda
Shigeharu
S
D015061:1,4-alpha-Glucan Branching Enzyme / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D001483:Base Sequence; D057005:Bioengineering; D002236:Carbohydrate Conformation; D017931:DNA Primers / Q000235:genetics; D004795:Enzyme Stability; D005798:Genes, Bacterial; D001411:Geobacillus stearothermophilus / Q000201:enzymology / Q000235:genetics; D005936:Glucans / Q000096:biosynthesis*; D005964:Glucosyltransferases / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013213:Starch / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity
D017931:DNA Primers; D005936:Glucans; D011994:Recombinant Proteins; C516208:cyclic nigerosylnigerose; D013213:Starch; D005964:Glucosyltransferases; D015061:1,4-alpha-Glucan Branching Enzyme