title: Properties of a novel thermostable glucoamylase from the hyperthermophilic archaeon Sulfolobus solfataricus in relation to starch processing.
abstract: A gene (ssg) encoding a putative glucoamylase in a hyperthermophilic archaeon, Sulfolobus solfataricus, was cloned and expressed in Escherichia coli, and the properties of the recombinant protein were examined in relation to the glucose production process. The recombinant glucoamylase was extremely thermostable, with an optimal temperature at 90 degrees C. The enzyme was most active in the pH range from 5.5 to 6.0. The enzyme liberated beta-d-glucose from the substrate maltotriose, and the substrate preference for maltotriose distinguished this enzyme from fungal glucoamylases. Gel permeation chromatography and sedimentation equilibrium analytical ultracentrifugation analysis revealed that the enzyme exists as a tetramer. The reverse reaction of the glucoamylase from S. solfataricus produced significantly less isomaltose than did that of industrial fungal glucoamylase. The glucoamylase from S. solfataricus has excellent potential for improving industrial starch processing by eliminating the need to adjust both pH and temperature.
authors.affiliation: National Research Laboratory for Functional Food Carbohydrate and Center for Agricultural Biomaterials, Seoul National University, Sillim-dong, Kwanak-gu, Seoul 151-742, Korea.
authors.forename: Mi-Sun
authors.initials: MS
authors.lastname: Kim
authors.forename: Jong-Tae
authors.initials: JT
authors.lastname: Park
authors.forename: Young-Wan
authors.initials: YW
authors.lastname: Kim
authors.forename: Hee-Seob
authors.initials: HS
authors.lastname: Lee
authors.forename: Rose
authors.initials: R
authors.lastname: Nyawira
authors.forename: Hyoun-Seung
authors.initials: HS
authors.lastname: Shin
authors.forename: Cheon-Seok
authors.initials: CS
authors.lastname: Park
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Yoo
authors.forename: Yong-Ro
authors.initials: YR
authors.lastname: Kim
authors.forename: Tae-Wha
authors.initials: TW
authors.lastname: Moon
authors.forename: Kwan-Hwa
authors.initials: KH
authors.lastname: Park
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D005087:Glucan 1,4-alpha-Glucosidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006031:Glycosylation; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification; D013213:Starch / Q000378:metabolism; D013379:Substrate Specificity; D016944:Sulfolobus / Q000201:enzymology*
chemical_list: D011994:Recombinant Proteins; D013213:Starch; D005087:Glucan 1,4-alpha-Glucosidase