Two glucose-forming enzymes were purified to an electrophoretically pure state from the extract of koji culture of Aspergillus awamori KT-11 using wheat bran. Both the enzymes hydrolyzed maltotriitol to produce an alpha-anomeric form of glucose and maltitol, and were identified as alpha-glucosidases (named alpha-G I and alpha-G II). The molecular weights were determined to be 108,000 for alpha-G I and 106,000 for alpha-G II by fast protein liquid chromatography, but their amino acid compositions were almost the same. The molecular weights of the subunits were estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to be 62,000 and 31,000 for the former and 59,000 and 31,000 for the latter. The optimum pH for bath enzymes was 5.2. The action pattern of these enzymes was almost the same, namely, hydrolysis of maltotetraose, isopanose, maltotriose, maltotriitol, panose, maltopentaose, maltose, maltohexaose, isomaltose, maltoheptaose in order of the initial reaction velocity, and their action was very weak on nigerose, maltitol and amylose to produce only glucose on a relatively low concentration of the substrates. However, neither acted on trehalose and sucrose. On the other hand, both strongly catalyzed the transfer action of a dense concentration of maltose to produce isomaltose, panose and other maltooligosaccharides with higher molecular weights than panose. The best conditions for the production of panose by the transfer action of alpha-G I were at pH 6.7 (yield, 31.0%), temperature 27 degrees C (yield, 34.3%) and 60% (w/v) of substrate concentration (yield 32.5%). From the results, both alpha-G I and alpha-G II were concluded to be novel enzymes.