Abstract
Long chain cis-prenyltransferase in rat liver microsomes was studied using various allylic isoprenoid substrates. Microsomes could utilize irans-geranyl pyrophosphate, but not cis-geranyl pyrophosphate for polyprenyl pyrophosphate synthesis. Both trans, trans-farnesyl pyrophosphate and trans,cis-farnesyl pyrophosphate were used as substrates with Km values of 24 and 5 μM, respectively. trans,trans,cis-Geranyl-geranyl pyrophosphate could be used as substrate with an apparent Km of 36μM. trans,trans,trans-Geranyl-geranyl pyrophosphate was also utilized as substrate, but with a very low affinity . After pulse labeling for 4 min, using [3H]isopentenyl pyrophosphate and trans, trans-farnesyl pyrophosphate, the only product formed was trans,trans,cis-geranylgeranyl pyrophosphate, which, upon chasing, yielded polyprenyl pyrophosphate. Independent of the nature of the substrate used, even in the case of polyprenyl 12-pyrophosphate and all-trans-nonaprenyl pyrophosphate, the chain lengths of the products were identical, i.e. polyprenyl pyrophosphates with 15-18 isoprene residues. Microsomes were able to synthesize trans, trans-farnesyl pyrophosphate using trans-geranyl pyrophosphate as substrate. The results indicate that rat liver microsomes contain a farnesyl pyrophosphate synthase activity and that the reaction catalyzed by cis-prenyl-transferase may consist of two individual steps, i.e. synthesis of trans,trans,cis-geranylgeranyl pyrophosphate and elongation of this product to long chain polyprenyl pyrophosphates.
| Original language | English |
|---|---|
| Pages (from-to) | 19730-19735 |
| Number of pages | 6 |
| Journal | Journal of Biological Chemistry |
| Volume | 267 |
| Issue number | 27 |
| Publication status | Published - 25 Sept 1992 |
| Externally published | Yes |