Aspergillus niger genome-wide analysis reveals a large number of novel alpha-glucan acting enzymes with unexpected expression profiles

The filamentous ascomycete Aspergillus niger is well known for its ability to produce a large variety of enzymes for the degradation of plant polysaccharide material. A major carbon and energy source for this soil fungus is starch, which can be degraded by the concerted action of α-amylase, glucoamylase and α-glucosidase enzymes, members of the...

Exo-inulinase of Aspergillus niger N402: A hydrolytic enzyme with significant transfructosylating activity

The purified exo-inulinase enzyme of Aspergillus niger N402 (AngInuE; heterologously expressed in Escherichia coli) displayed a sucrose:inulin (S/I) hydrolysis ratio of 2.3, characteristic for a typical exo-inulinase. The enzyme also had significant transfructosylating activity with increasing sucrose concentrations, producing various...

Identification of acceptor substrate binding subsites +2 +3 in the amylomaltase from Thermus thermophilus HB8

Glycoside hydrolase family 77 (GH77) belongs to the α-amylase superfamily (Clan H) together with GH13 and GH70. GH77 enzymes are amylomaltases or 4-α-glucanotransferases, involved in maltose metabolism in microorganisms and in starch biosynthesis in plants. Here we characterized the amylomaltase from the hyperthermophilic bacterium Thermus...

Three-way stabilization of the covalent intermediate in amylomaltase, an alpha-like transglycosylase

Amylomaltases are glycosyl hydrolases belonging to glycoside hydrolase family 77 that are capable of the synthesis of large cyclic glucans and the disproportionation of oligosaccharides. Using protein crystallography, we have generated a flip book movie of the amylomaltase catalytic cycle in atomic detail. The structures include a covalent...

Properties and applications of starch-converting enzymes of the alpha-amylase family

Starch is a major storage product of many economically important crops such as wheat, rice, maize, tapioca, and potato. A large-scale starch processing industry has emerged in the last century. In the past decades, we have seen a shift from the acid hydrolysis of starch to the use of starch-converting enzymes in the production of maltodextrin,...

Enzymatic extractability of soybean meal proteins and carbohydrates: Heat and humidity effects

To study the incomplete enzymatic extractability of proteins and carbohydrates of thermally treated soybean meals, one unheated and three heat-treated soybean meals were produced. To obtain truly enzyme-resistant material, the meals were extracted by a repeated hydrolysis procedure using excessive concentrations of different combinations of...

Localization of synthesis of β1,6-glucan in Saccharomyces cerevisiae

β1,6-Glucan is a key component of the yeast cell wall, interconnecting cell wall proteins, β1,3-glucan, and chitin. It has been postulated that the synthesis of β1,6-glucan begins in the endoplasmic reticulum with the formation of protein-bound primer structures and that these primer structures are extended in the Golgi complex by two putative...

Characterization of O-glycosylated precursors of insulin-like growth factor II by matrix-assisted laser desorption/ionization mass spectrometry

High molecular weight precursors of insulin-like growth factor II (IGF-II) were isolated from Cohn fraction IV of human plasma by ultrafiltration, affinity chromatography and reversed-phase high-performance liquid chromatography. Molecular weight determination by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of two...

Expression of Bacillus subtilis levanase gene in Lactobacillus plantarum and Lactobacillus casei

Two Lactobacillus-Escherichia coli shuttle vectors, harbouring the levanase gene from Bacillus subtilis under the control of its own promoter (pLPEW1) or behind the E. coli tac promoter (pE-SIEW2), were constructed. Lactobacillus plantarum showed the same growth characteristics on selective plates and in liquid media containing inulin, after...