Chemical modification and amino acid sequence of active site in sugar beet alpha-glucosidase.
The modification of amino acid residues in sugar beet alpha-glucosidase with conduritol B epoxide (CBE), an affinity labeling reagent, inactivated the enzyme. The inactivation followed pseudo-first-order kinetics. The enzyme was protected from inactivation by a competitive inhibitor, Tris, and the partially inactivated enzymes showed only the decrease of V values and no change in Km value. An 3H-CBE labeled peptide isolated from the digest of the inactivated enzyme with Lys-C protease was sequenced. The -COO- group of Asp was found to be specifically labeled, implicating that it is a catalytic group of the enzyme. The sequence around the essential Asp was determined to be -DGIWIDMNE-, which showed a high homology with those of other alpha-glucosidases.
Iwanami
S
S
Faculty of Agriculture, Hokkaido University, Sapporo, Japan.
Matsui
H
H
Kimura
A
A
Ito
H
H
Mori
H
H
Honma
M
M
Chiba
S
S
D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D004586:Electrophoresis; D065089:Glycoside Hydrolase Inhibitors; D007294:Inositol / Q000031:analogs & derivatives / Q000737:chemistry; D007700:Kinetics; D008969:Molecular Sequence Data; D010944:Plants / Q000201:enzymology*; D011487:Protein Conformation; D014461:Ultracentrifugation; D000520:alpha-Glucosidases / Q000737:chemistry*; D001617:beta-Glucosidase / Q000037:antagonists & inhibitors
D065089:Glycoside Hydrolase Inhibitors; D007294:Inositol; D000520:alpha-Glucosidases; D001617:beta-Glucosidase; C011423:conduritol epoxide