A novel amylolytic enzyme from Thermotoga maritima, resembling cyclodextrinase and alpha-glucosidase, that liberates glucose from the reducing end of the substrates.
The gene previously designated as putative cyclodextrinase from Thermotoga maritima (TMG) was cloned and overexpressed in Escherichia coli. The recombinant TMG was partially purified and its enzymatic characteristics on various substrates were examined. The enzyme hydrolyzes various maltodextrins including maltotriose to maltoheptaose and cyclomaltodextrins (CDs) to mainly glucose and maltose. Although TMG could not degrade pullulan, it rapidly hydrolyzes acarbose, a strong amylase and glucosidase inhibitor, to acarviosine and glucose. Also, TMG initially hydrolyzes p-nitrophenyl-alpha-pentaoside to give maltopentaose and p-nitrophenol, implying that the enzyme specifically cleaves a glucose unit from the reducing end of maltooligosaccharides unlike to other glucosidases. Since its enzymatic activity is negligible if alpha-methylglucoside is present in the reducing end, the type of the residue at the reducing end of the substrate is important for the TMG activity. These results support the fact that TMG is a novel exo-acting glucosidase possessing the characteristics of both CD-/pullulan hydrolyzing enzyme and alpha-glucosidase.
Lee
Myoung Hee
MH
Research Center for New Bio-Materials in Agriculture and Department of Food Science and Technology, School of Agricultural Biotechnology, Seoul National University, Suwon, Republic of Korea.
Kim
Young Wan
YW
Kim
Tae Jip
TJ
Park
Cheon Seok
CS
Kim
Jung Wan
JW
Moon
Tae Wha
TW
Park
Kwan Hwa
KH
D020909:Acarbose / Q000378:metabolism; D000595:Amino Acid Sequence; D000606:Amino Sugars / Q000378:metabolism; D000682:Amyloid / Q000378:metabolism*; D002384:Catalysis; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D005936:Glucans / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000737:chemistry*; D006868:Hydrolysis; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D020124:Thermotoga maritima / Q000201:enzymology*; D000520:alpha-Glucosidases / Q000378:metabolism*
D000606:Amino Sugars; D000682:Amyloid; D005936:Glucans; D009844:Oligosaccharides; D011994:Recombinant Proteins; C076099:acarviosine; C009109:pullulan; D004247:DNA; D006026:Glycoside Hydrolases; D000520:alpha-Glucosidases; C048745:cyclomaltodextrinase; D005947:Glucose; D020909:Acarbose