title: Characterization of novel thermophilic alpha-glucosidase from Bifidobacterium longum.
abstract: In this study, the gene encoding α-glucosidase from Bifidobacterium longum subsp. longum JCM1217 (BLAG) was cloned and expressed in Escherichia coli. The amino acid sequence alignment demonstrated that BLAG belongs to glycoside hydrolase (GH) family 13. The optimal temperature for enzyme activity was 75°C; about 80% of the catalytic activity was lost at 50°C, which is very unusual for enzymes from the Bifidobacterium genus. In the presence of 5mM of Co2+and Ca2+, enzyme activity was reduced to 47% and 48%, respectively. Furthermore, BLAG lost catalytic activity following the addition of 5mM of Fe2+ion. The BLAG enzyme was able to hydrolyze α-1,2, α-1,3, α-1,4, and α-1,6 glycosidic O-linkages and liberated glucose from the non-reducing end of substrates. The kinetic study revealed that among the maltooligosaccharides, BLAG showed the highest kcat/Kmvalue to maltotriose (G3), and had relatively low kcat/Kmvalues on long-chain maltooligosaccharides. This is the first report describing the production of a thermophilic α-glucosidase from the Bifidobacterium genus.
authors.affiliation: Department of Food Science and Nutrition and Center for Aging and Health Care, Hallym University, 1 Hallymdaehak-gil, Chuncheon, Gangwon-do, 24252, Republic of Korea.
authors.forename: Na-Ri
authors.initials: NR
authors.lastname: Kim
authors.affiliation: Department of Food Science and Nutrition and Center for Aging and Health Care, Hallym University, 1 Hallymdaehak-gil, Chuncheon, Gangwon-do, 24252, Republic of Korea.
authors.forename: Da-Woon
authors.initials: DW
authors.lastname: Jeong
authors.affiliation: Department of Food Science and Nutrition and Center for Aging and Health Care, Hallym University, 1 Hallymdaehak-gil, Chuncheon, Gangwon-do, 24252, Republic of Korea.
authors.forename: Dam-Seul
authors.initials: DS
authors.lastname: Ko
authors.affiliation: Department of Food Science and Nutrition and Center for Aging and Health Care, Hallym University, 1 Hallymdaehak-gil, Chuncheon, Gangwon-do, 24252, Republic of Korea. Electronic address: jhshim@hallym.ac.kr.
authors.forename: Jae-Hoon
authors.initials: JH
authors.lastname: Shim
mesh_terms: D000069978:Bifidobacterium longum / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals / Q000494:pharmacology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013696:Temperature; D000520:alpha-Glucosidases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D008670:Metals; D011994:Recombinant Proteins; D000520:alpha-Glucosidases
keywords: Alpha glucosidase; Bifidobacterium longum; Glycoside hydrolase; Thermophile; Thermostability