Non-caloric sweetener

摘要

Disclosed is a steviol glycoside referred to as rebaudioside D3. Rebaudioside D3 has five β-D-glucosyl units connected to the aglycone steviol. Also disclosed are methods for producing rebaudioside D3, a UDP-glycosyltransferase fusion enzyme, and methods for producing rebaudioside D and rebaudioside E.

主权项

1. A method for synthesizing rebaudioside D3, the method comprising: preparing a reaction mixture comprising stevioside; a substrate selected from the group consisting of sucrose, uridine diphosphate and uridine diphosphate-glucose; and a UDP-glycosyltransferase fusion enzyme comprising a uridine diphospho glycosyltransferase domain coupled to a sucrose synthase domain; and incubating the reaction mixture for a sufficient time to produce rebaudioside D3, wherein the UDP-glycosyltransferase is a Oryza sativa uridine diphospho glycosyltransferase EUGT11 comprising the amino acid sequence of SEQ ID NO:1, wherein a glucose is covalently coupled to the stevioside to produce a rebaudioside E intermediate, and wherein a glucose is covalently coupled to the rebaudioside E intermediate to produce rebaudioside D3.