Figure 5.

Homogentisate polyprenyltransferase assays. Individual reactions contained the indicated prenyl-DP and protein extracts from E. coli expressing empty vector or the indicated phytyltransferases. Radiolabeled prenylquinol reaction products were extracted, oxidized to corresponding quinones, separated by TLC, and subjected to autoradiography. SynHPT can utilize both PDP and GGDP as prenyl-DP substrates (lanes 6 and 7), whereas AtHPT can only use PDP (lane 10). Neither enzyme could catalyze condensation of HGA and SDP (lanes 8 and 12). No prenylquinone products were detected in control reactions (lanes 1–5 and 9). The arrow indicates the origin.