Properties of a novel thermostable glucoamylase from the hyperthermophilic archaeon Sulfolobus solfataricus in relation to starch processing.
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.
Kim
Mi-Sun
MS
National Research Laboratory for Functional Food Carbohydrate and Center for Agricultural Biomaterials, Seoul National University, Sillim-dong, Kwanak-gu, Seoul 151-742, Korea.
Park
Jong-Tae
JT
Kim
Young-Wan
YW
Lee
Hee-Seob
HS
Nyawira
Rose
R
Shin
Hyoun-Seung
HS
Park
Cheon-Seok
CS
Yoo
Sang-Ho
SH
Kim
Yong-Ro
YR
Moon
Tae-Wha
TW
Park
Kwan-Hwa
KH
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*
D011994:Recombinant Proteins; D013213:Starch; D005087:Glucan 1,4-alpha-Glucosidase