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Purification and Some Properties of an Extremely Thermostable Trehalose‐hydrolyzing α‐Glucosidase from Bacillus flavocaldarius KP1228
Author(s) -
Murakami S.,
Yagami M.,
Suzuki Y.
Publication year - 1998
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/(sici)1521-379x(199803)50:2/3<100::aid-star100>3.0.co;2-r
Subject(s) - trehalose , maltose , chemistry , maltotriose , isoelectric point , chromatography , thermostability , hydrolysis , size exclusion chromatography , gel electrophoresis , isomaltose , polyacrylamide gel electrophoresis , melibiose , biochemistry , enzyme
An intracellular trehalose‐hydrolase of the extreme thermophile Bacillus flavocaldarius KP1228 (FERM‐P9542) was purified to homogeneity. The molecular weight of the enzyme was estimated as 102,000 by sodium dodecylsulfate‐polyacrylamide gel electrophoresis, but as 420,000 by gel filtration and gel electrophoresis under native conditions. Its Stoke 's radius, frictional ratio and isoelectric point were estimated as 7.0 nm, 1.4 and 4.43, respectively. The enzyme was most active at 78°C and pH 6.2. Its half‐life was 10 min at 90°C and pH 6.5. The enzyme hydrolyzed α‐glucosidic bonds of trehalose, maltose, sucrose and p‐nitrophenyl‐α‐ D ‐glucopyranoside (each at 10 m M ) with respective relative rates of 100, 130, 11 and 7.8 at 80°C and pH 6.8, but neither of α‐glucosidic bonds in isomaltose, dextrin nor soluble starch. The Michaelis constant and the molecular activity (/subunit) were 85 m;M and 4.0 s −1 for trehalose, and 61 m;M and 4.2 s −1 for maltose, respectively. We have suggested that the enzyme is a novel thermostable homotetrameric α‐glucosidase (α‐ D ‐glucoside glucohydrolase, EC 3.2.1.20) active on both α‐1,1 bond of trehalose and α‐1,4 bond of maltose.