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Starch-Processing Enzymes Produced by Recombinant Yeasts and Fungi
Published in Yoshikatsu Murooka, Tadayuki Imanaka, Recombinant Microbes for Industrial and Agricultural Applications, 2020
Comparison of the active site sequences surrounding the Glu-180 in glucoamylase, Asp-505 in isomaltase, and Asp-214 in maltase led to the postulation that Trp-178 and Asn-182 of glucoamylase are associated with the activity to affect an exoattack on α-(1-6) glucosidic bonds ] 119]. Two mutants, Trp-178→Arg and Asn-182→Ala, were constructed to make glucoamylase conform more closely to the α-(l-4) hydrolase, resulting in increased selectivity for maltose [119]. The Asn-182->Ala mutant showed no loss of activity. This has potential technical applications, since prolonged reaction with the wild-type enzyme at high glucose concentrations results in accumulation of the condensation product isomaltose in the reverse reaction, reducing the yield in the production of glucose syrup [119]
Modeling and evaluation of the sucrose-degrading activity of recombinantly produced oligo-1,6-glucosidase from A. gonensis
Published in Preparative Biochemistry & Biotechnology, 2023
Hakan Karaoglu, Zeynep Dengız Balta
According to the CAZy database (http://www.cazy.org/), oligo-1,6-glucosidase (O-1-6-glucosidase) (EC 3.2.1.10) is a member of the glycoside hydrolase family 13 subfamily 31 (GH13_31).[10] O-1-6-glucosidase hydrolyzes non-reducing ends of isomaltooligosaccharides, panose, palatinose, and an a-limit dextrin by breaking α-1,6-glucoside bonds, although it generally lacks activity on α-1,4-glucoside bonds of maltooligosaccharides.[11] The enzyme is also called isomaltase, sucrase-isomaltase, dextrin 6-α-D glucanohydrolase, palatinase, and α-limit dextrinase. O-1-6-glucosidase is commonly used in the saccharification step of HFS production because it hydrolyzes branched oligosaccharides of short lengths and increasing glucose yield.[12] O-1-6-glucosidase can also hydrolyze sucrose to its monomers, glucose and fructose (Figure 1), which are valuable for HFS.[13] While, sucrose hydrolyzing activity was not studied for HFS production before, isomaltooligosaccharides hydrolyzing activity of O-1-6-glucosidase has been well-studied.[14] The microorganisms surviving above the temperature of 40 °C are categorized as thermophilic. Thermophilic microorganisms generally inhabit hot springs and have unique metabolites, especially physically and chemically stable enzymes. Recently, thermophilic microorganisms and their enzymes have been extensively researched due to their advantages for industrial applications.[15]