Browsing by Author "Takeshi Yamamoto"

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    Purification and characterization of α-glucosidase I from Japanese honeybee (Apis cerana japonica) and molecular cloning of Its cDNA
    (2006-12-01) Jintanart Wongchawalit; Takeshi Yamamoto; Hiroyuki Nakai; Young Min Kim; Natsuko Sato; Mamoru Nishimoto; Masayuki Okuyama; Haruhide Mori; Osamu Saji; Chanpen Chanchao; Siriwat Wongsiri; Rudee Surarit; Jisnuson Svasti; Seiya Chiba; Atsuo Kimura; Hokkaido University; Fukushima Museum; Chulalongkorn University; Mahidol University
    α-Glucosidase (JHGase I) was purified from a Japanese subspecies of eastern honeybee (Apis cerana japonica) as an electrophoretically homogeneous protein. Enzyme activity of the crude extract was mainly separated into two fractions (component I and II) by salting-out chromatography. JHGase I was isolated from component I by further purification procedure using CM-Toyopearl 650M and Sephacryl S-100. JHGase I was a monomeric glycoprotein (containing 15% carbohydrate), of which the molecular weight was 82,000. Enzyme displayed the highest activity at pH 5.0, and was stable up to 40°C and in a pH-range of 4.5-10.5. JHGase I showed unusual kinetic features: the negative cooperative behavior on the intrinsic reaction on cleavage of sucrose, maltose, and p-nitrophenyl α-glucoside, and the positive cooperative behavior on turanose. We isolated cDNA (1,930 bp) of JHGase I, of which the deduced amino-acid sequence (577 residues) confirmed that JHGase I was a member of α-amylase family enzymes. Western honeybees (Apis mellifera) had three α-glucosidase isoenzymes (WHGase I, II, and III), in which JHGase I was considered to correspond to WHGase I.