Cyclization reaction catalyzed by glycogen debranching enzyme (EC 2.4.1.25/EC 3.2.1.33) and its potential for cycloamylose production.
Glycogen debranching enzyme (GDE) has 4-alpha-glucanotransferase and amylo-1,6-glucosidase activities in the single polypeptide chain. We analyzed the detailed action profile of GDE from Saccharomyces cerevisiae on amylose and tested whether GDE catalyzes cyclization of amylose. GDE treatment resulted in a rapid reduction of absorbance of iodine-amylose complex and the accumulation of a product that was resistant to an exo-amylase (glucoamylase [GA]) but was degraded by an endo-type alpha-amylase to glucose and maltose. These results indicated that GDE catalyzed cyclization of amylose to produce cyclic alpha-1,4 glucan (cycloamylose). The formation of cycloamylose was confirmed by high-performance anion-exchange chromatography, and the size was shown to range from a degree of polymerization of 11 to a degree of polymerization around 50. The minimum size and the size distribution of cycloamylose were different from those of cycloamylose produced by other 4-alpha-glucanotransferases. GDE also efficiently produced cycloamylose even from the branched glucan substrate, starch, demonstrating its potential for industrial production of cycloamylose.
Biochemical Research Laboratory, Ezaki Glico Co., Ltd., Nishiyodogawa-ku, Osaka 555-8502, Japan. yanase-michiyo@glico.co.jp
Michiyo
M
Yanase
Hiroki
H
Takata
Takeshi
T
Takaha
Takashi
T
Kuriki
Steven M
SM
Smith
Shigetaka
S
Okada
D000688:Amylose / Q000378:metabolism*; D002384:Catalysis; D003500:Cyclization; D003505:Cyclodextrins / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006004:Glycogen Debranching Enzyme System / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013379:Substrate Specificity
D003505:Cyclodextrins; D006004:Glycogen Debranching Enzyme System; D000688:Amylose; D005947:Glucose