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Figure 1.
Figure 1. Scheme of the CGTase reaction mechanism. The first
step, leading to intermediate formation, is explained in the
text. In the second step, Glu 257 activates an acceptor that
subsequently reacts with the intermediate, leading to product
formation. This proceeds with a mechanism that is essentially
the reverse of the first step. The glucoside ring atom
nomenclature is incorporated in the left-most picture. The
shaded orbital represents the electrons that are in a proper
orientation to participate in the cleavage of the substrate  -glycosidic
bond according to the stereo-electronic theory^22. However, when
the intermediate  -glycosyl-enzyme
bond is cleaved, such a correctly oriented orbital is not
present, as pointed out in the text.
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