Corrins and the Acetyl-CoA Path of Autotrophic Fixation of Carbon Dioxide in Bacteria

Abstract

Autotrophic fixation of carbon dioxide in bacteria proceedes not only via the well-known «Calvin cycle», but also via the recently established «acetyl-coenzyme A pathway», meanwhile found to be widely distributed in bacterial anaerobes. In this linear path of carbon dioxide assimilation, a series of transition metal enzymes are engaged in the build-up of (the acetyl group of) acetyl-coenzyme A from carbon dioxide and molecular hydrogen. Corrins are given a central, if chemically still incompletely defined role in the crucial carbon-carbon bond forming step and correspondingly are abundant cofactors in the bacteria that follow this pathway. Detailed knowledge on the chemistry of this remarkable «organometallic» way for the fixation of carbon dioxide in nature not only is of interest in its own right, but also in view of the search for economic syntheses of basic organic chemicals and «fuels» from carbon dioxide.