Electronic mechanistic pattern for C-C bond-breaking from transition structures in Rubisco's chemistry

The transition structures (TSs) for the carbon-carbon bond-breaking step in the carboxylation and oxygenation reactions catalyzed by Rubisco are studi ed at HF/6-31G** and full MP2/6-31G** levels. The active atoms of the subst rate (ribulose 1,5-bisphosphate) are modeled with 3- and 5-carbon atom mole cules. A model coordination sphere is included in order to detect the role of magnesium on the TS. The electron localization function ((ELF) is used t o obtain the basin structure of the transition structures, giving a pictori al description of the wave function allowing for a distinction between hete rolytic-like and homolytic-like mechanisms for the C2-C3 breaking process. (C) 2001 Elsevier Science B.V. All rights reserved.