Prenyltransferase: the mechanism of the reaction.

The enzyme, prenyltransferase, which normally catalyzes the addition of an allylic pyrophosphate to isopentenyl pyrophosphate, has been found to catalyze the hydrolysis of its allylic substrate. The rate of this hydrolysis is markedly stimulated by inorganic pyrophosphate. Competition experiments with 2-fluoroisopentenyl pyrophosphate and inorganic pyrophosphate demonstrated that inorganic pyrophosphate stimulated hydrolysis by binding at the isopentenyl pyrophosphate site. Hydrolysis carried out in H218O or with (1S)-[1-3H]geranyl pyrophosphate show the C-O bond is broken and the C1 carbon of geranyl pyrophosphate is inverted in the process. These results are interpreted to favor a carbonium ion mechanism for the prenyltransferase reaction.     

Treatment of H. pylori infection: the reality.

Despite the wide dissemination of information on Helicobacter pylori, there is still a great deal of variation in how general practitioners treat the infection and in which circumstances they prescribe eradication therapy for H. pylori. Specialty societies have developed consensus guidelines that recommend a strategy to test and treat dyspeptic patients for H. pylori infection although the data to support these recommendations are weak at the present time. As a result, there is still confusion about the indications for treatment and the treatment regimens that are likely to be effective in routine clinical practice.