| Stereospecificity and mechanism of monoterpene cyclases have been investigated by use of deuterium and tritium labeled substrates. The stereochemistry of the terminating deprotonation in limonene biosynthesis was elucidated by radiochemical degradation of (;(3R,4R)-(;Aza and thia analogs of presumed ;3-Aza-GGPP was found to inhibit GGPP synthase selectively in the presence of FPP synthase. Comparison of the inhibitory effects of (E,E,E)-, (Z,E,E)-, and 3-aza-GGPP supports the notion of a carbocation intermediate in the chain elongation process. However, 3-aza-GGPP was not an effective inhibitor for dehydrodolichyl PP synthase and farnesyl:protein transferase. Although the analog was found to inhibit geranylgeranyl:protein transferase, its binding affinity was about 10 times weaker than that of GGPP. In preliminary assays, (... |
