Fig. 3: Schematic diagram of the whole process for generating the branching product. | Nature Communications

Fig. 3: Schematic diagram of the whole process for generating the branching product.

From: Elucidation of the noncovalent interactions driving enzyme activity guides branching enzyme engineering for α-glucan modification

Fig. 3: Schematic diagram of the whole process for generating the branching product.

In (a), step i, the substrate is G7. The constructed RpBE was employed as the structural model; For clarity, the enzyme is displayed with an opaque representation in a, but with a semi-transparent one in b,d and e. In (b), step ii, D305, E356, and D424 form the catalytic triad in RpBE. ES I denotes the noncovalent enzyme-substrate complex before glycosylation. In (c), step iii, TS1 and CI denote the transition state in the course of glycosylation and the formed enzyme-substrate covalent intermediate (CI) after glycosylation, respectively. In (d), step iv, the acceptor chain (cyan) binds to the enzyme. In (e), step v, the acceptor chain moves to the catalytic position and prepares for transglycosylation, wherein the donor chain (green) will be linked as a branch to the hydroxyl on C6 of the cyan acceptor chain. ES II denotes the enzyme-substrate complex before transglycosylation. In (f), step vi, TS2 and EP denote the transition state in transglycosylation and the noncovalent enzyme-product complex after catalysis, respectively; the product is the α−1,6-glucosidic branching glucan.

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