A Novel α-Glucosidase of the Glycoside Hydrolase Family 31 from <i>Aspergillus sojae</i>

Abstract

We characterized an α-glucosidase belonging to the glycoside hydrolase family 31 from Aspergillus sojae. The α-glucosidase gene was cloned using the whole genome sequence of A. sojae, and the recombinant enzyme was expressed in Aspergillus nidulans. The enzyme was purified using affinity chromatography. The enzyme showed an optimum pH of 5.5 and was stable between pH 6.0 and 10.0. The optimum temperature was approximately 55 °C. The enzyme was stable up to 50 °C, but lost its activity at 70 °C. The enzyme acted on a broad range of maltooligosaccharides and isomaltooligosaccharides, soluble starch, and dextran, and released glucose from these substrates. When maltose was used as substrate, the enzyme catalyzed transglucosylation to produce oligosaccharides consisting of α-1,6-glucosidic linkages as the major products. The transglucosylation pattern with maltopentaose was also analyzed, indicating that the enzyme mainly produced oligosaccharides with molecular weights higher than that of maltopentaose and containing continuous α-1,6-glucosidic linkages. These results demonstrate that the enzyme is a novel α-glucosidase that acts on both maltooligosaccharides and isomaltooligosaccharides, and efficiently produces oligosaccharides containing continuous α-1,6-glucosidic linkages.

Associations between Wastewater Microbiome and Population Smoking Rate Identified Using Wastewater-Based Epidemiology

“…In comparison, GH31 (containing α-glucosidases) present in three screened representative microorganisms (Blautia, Lactococcus and Enterococcus) suggested that starch and cellulose metabolism is more active in microorganisms associated with the low smoking population. 83 This observation is also verified by COG and KEGG. Among the 26 screened COGs, those associated with transcription, antibiotic resistance, and nucleic acid metabolism were predominantly linked to a high smoking rate, while the differentially represented KOs associated with a low smoking rate were primarily involved in carbohydrate, amino acid, and energy metabolism.…”

Analysis of Transglucosylation Products of <i>Aspergillus niger</i> α-Glucosidase that Catalyzes the Formation of α-1,2- and α-1,3-Linked Oligosaccharides

“…The results of these assays were compared with those previously reported for AgdA. 19) The activities of AgdB and AgdA were determined based on the relative amounts of glucose released from their substrates. No trehalose-hydrolyzing activity was detected.…”

“…a Kinetic parameter of A. niger AgdA cited from a previous report. 19) b Weighted average molecular weight of soluble starch was 8,778 determined by gel permeation chromatography.…”

“…have often been used as industrial enzyme sources with the α-glucosidases from A. niger , A. sojae , A. nidulans , and A. oryzae demonstrating the capacity to catalyze transglucosylation resulting in products with primarily α-1,6-glucosidic linkages. 5) 19) 20) 24) Alternatively, AgdB can produce both α-1,2- and α-1,3-linked oligosaccharides and may be capable of doing so on an industrial scale. However, the physiological functions of the oligosaccharides produced by AgdB have not yet been characterized, and thus require further investigation.…”

“…The transglucosylation products were analyzed and fractionated by high performance liquid chromatography (HPLC) as previously described. 19) To determine the degree of polymerization (DP), the HPLC system was run in the MCI GEL CK04S column (Mitsubishi Chemical Corp., Tokyo, Japan) with a refractive index detector (RID-10A; Shimazu Corp., Kyoto, Japan). The transglucosylation products were eluted with distilled water.…”