Localization of α-Glucosidases I, II, and III in Organs of European Honeybees,Apis melliferaL., and the Origin of α-Glucosidase in Honey

Abstract

Three kinds of alpha-glucosidases, I, II, and III, were purified from European honeybees, Apis mellifera L. In addition, an alpha-glucosidase was also purified from honey. Some properties, including the substrate specificity of honey alpha-glucosidase, were almost the same as those of alpha-glucosidase III. Specific antisera against the alpha-glucosidases were prepared to examine the localization of alpha-glucosidases in the organs of honeybees. It was immunologically confirmed for the first time that alpha-glucosidase I was present in ventriculus, and alpha-glucosidase II, in ventriculus and haemolymph. alpha-Glucosidase III, which became apparent to be honey alpha-glucosidase, was present in the hypopharyngeal gland, from which the enzyme may be secreted into nectar gathered by honeybees. Honey may be finally made up through the process whereby sucrose in nectar, in which glucose and fructose also are naturally contained, is hydrolyzed by secreted alpha-glucosidase III.

Purification and Characterization of α-Glucosidase I from Japanese Honeybee (Apis cerana japonica) and Molecular Cloning of Its cDNA

“…We purified an -glucosidase from honey. 10) The properties of honey enzyme coincided completely with WHGase III, indicating a significant physiological role of WHGase III in the honey-formation process. WHGase III, secreted from hypopharyngeal gland to the nectar gathered by honeybees, was responsible for converting sucrose (main carbohydrate in nectar) to glucose and fructose (main components in honey).…”

“…5,6) Three -glucosidases were different in molecular size, pH-stability, temperature-stability, substrate specificity, and localization in organ. [5][6][7][8][9][10] They were glycoproteins containing sugar content of 25% (WHGase I), 15% (WHGase II), and 7.4% (WHGase III), which might y To whom correspondence should be addressed. Tel/Fax: +81-11-706-2808; E-mail: kimura@abs.agr.hokudai.ac.jp Abbreviations: DP, average degree of polymerization of glucose; GH, glycoside hydrolase family; JHGase I, Japanese honeybee -glucosidase isoenzyme I; PAGE, polyacrylamide gel electrophoresis; pNPG, p-nitrophenyl -glucoside; RACE, rapid amplification of cDNA end; WHGase I, WHGase II, and WHGase III, western honeybee -glucosidase isoenzyme I, II, and III, respectively affect solubility in ammonium sulfate separation of the purification procedure.…”

Amino Acids in Conserved Region II Are Crucial to Substrate Specificity, Reaction Velocity, and Regioselectivity in the Transglucosylation of Honeybee GH-13 α-Glucosidases

“…Pro226-Tyr227 of HBG-III and their equivalents are indicated by bold-faced letters. The partial sequences, listed from the top, are of -glucosidase isozymes III, II, and I from Apis mellifera (HBG-III, HBG-II, and HBG-I respectively), 6,12) Taka-amylase from Aspergillus oryzae, 25) Bacillus subtilisamylase, 26) sucrose hydrolase SUH from Xanthomonas axonopodis, 27) sucrose phosphorylase from Bifidobacterium adolescentis, 28) amylosucrase from Neisseria polysaccharea, 30) trehalulose synthase (MutB) from Psuedomonas mesoacidophila, 31) and dextran glucosidase (SmDG) from Streptococcus mutans. 29) hydrolysate (6 N HCl at 110 C for 24 h) by the ninhydrin colorimetric method using an amino acid analyzer (AminoTac JLC/500V, JEOL, Tokyo).…”

“…HBG-III is secreted from the hypopharyngeal grand into the nectar and is involved in honey formation. 6) These enzymes are clearly different in substrate specificity, ability to catalyze transglucosylation, and regioselectivity in transglucosylation. HBG-I shows little or no activity toward nigerose, isomaltose, or soluble starch.…”

Honey bee drones maintain humoral immune competence throughout all life stages in the absence of vitellogenin production

“…Three kinds of glucosidases were purified from honey bees. It was immunologically confirmed that -glucosidase I is present in the ventriculus, -glucosidase II is present in the ventriculus and the haemolymph, and -glucosidase III is present in the hypopharyngeal gland, the latter enzyme being identical with the -glucosidase present in honey (Kubota et al, 2004). The physiological function of -glucosidase II is not yet known.…”