Undecaprenyl pyrophosphate synthetase from Lactobacillus plantarum: A dimeric protein

Undecaprenyl pyrophosphate synthetase has been purified from Lactobacillus plantarum. It catalyzes the formation of a C 55 polyprenyl pyrophosphate having isoprene residues with cis stereochemistry. The enzyme was shown to be an acidic protein (p I = 5.1), which can be partially purified by preparative gel electrophoresis and Blue-agarose column chromatography. The K m 's of the enzyme for its substrates t,t-farnesyl pyrophosphate and isopentenyl pyrophosphate were determined to be 0.13 and 1.92 μ m, respectively. The molecular weight of the enzyme was estimated by molecular sieve chromatography and gradient centrifugation to be 56,000 ± 4000. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the protein was composed of a dimer of 30,000-Da subunits. The enzyme was inactivated by the arginine-specific reagents phenylglyoxal, butanedione and, cyclohexanedione, but this inactivation was not prevented by either of the substrates.