- The AcbC protein from Actinoplanes species is a C7-cyclitol synthase related to 3-dehydroquinate synthases and is involved in the biosynthesis of the alpha-glucosidase inhibitor acarbose. Stratmann, A., Mahmud, T., Lee, S., Distler, J., Floss, H.G., Piepersberg, W. J. Biol. Chem. (1999)