Synthesis of highly branched α-glucans with different structures using GH13 and GH57 glycogen branching enzymes.
Glycogen branching enzymes (GBEs) convert starch into branched α-glucan polymers. To explore if the amylose content of substrates effects the structure of the branched α-glucans, mixtures of amylose and amylopectin were converted by four thermophilic GBEs. The degree of branching and molecular weight of the products increased with an increasing percentage of amylose with the GH57 GBEs of Thermus thermophilus and Thermococcus kodakarensis, and the GH13 GBEs of Rhodothermus marinus and Petrotoga mobilis. The only exception is that the degree of branching of the Petrotoga mobilis GBE products is not influenced by the amylose content. A second difference is the relatively high hydrolytic activity of two GH57 GBEs, while the two GH13 GBEs have almost no hydrolytic activity. Moreover, the two GH13 GBEs synthesize branched α-glucans with a narrow molecular weight distribution, while the two GH57 GBEs products consist of two or three molecular weight fractions.
['Zhang|Xuewen|X|', 'Leemhuis|Hans|H|', 'van der Maarel|Marc J E C|MJEC|']
D015061:1,4-alpha-Glucan Branching Enzyme D000687:Amylopectin D000688:Amylose D057075:Enzyme Assays D004926:Escherichia coli D005936:Glucans D006868:Hydrolysis D008970:Molecular Weight D016963:Thermus thermophilus
α-glucan Glycogen branching enzyme Amylose Amylopectin Glycoside hydrolase