| 摘要 |
&bgr;-Amyrin, a precursor in biosynthesis of soyasapogenol B, is biosynthesized by cyclization of 2,3-oxidosqualene which is generated by the mevalonate pathway, and soyasapogenol B is biosynthesized by two hydroxylations of &bgr;-amyrin. However, a gene of 22-hydroxylase involved in the sequence of reactions has not been identified. The present inventors identified a gene encoding the hydroxylase for oleanene triterpenes at C-22, and found that oleanene triterpenes could be hydroxylated at C-22 by co-expressing this gene together with one or more specific genes. Further, the present inventors found that soyasapogenol B could be efficiently produced in large quantities by co-expressing this gene for 22-hydroxylase with a gene for 24-hydroxylase.
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