Nonoxidative PPP

Exposing the Problem of Assigning a Reaction Scheme to the Nonoxidative PPP... 

With the above background, between 1950 and 1955, a breathtaking series followed of discoveries of enzyme and substrate reactivities that were destined to be incorporated into a reaction scheme (mechanism) for the classic nonoxidative PPP (Fig. 2). The Fig. 2 diagram has also been given the prefix F-type (for fat-cell) PPP Williams et al. (1), because its ordered reaction sequence was later shown to measure uniquely a large contribution (50%) to metabolism when Glc was converted to fatty... 

B. The PPP operates in two phases an oxidative phase and a nonoxidative phase. 

The history of the unravelling of many of the above events reveals instances of profound weakness in evidence used to justify the nonoxidative pathway description. These instances are identihed and discussed in this overview and show that textbook depictions of PPP are so incomplete and misleading that the scheme for the pathway is deemed erroneous. 

A synoptic survey of the unravelling of the nonoxidative segment is presented in the latest comprehensive review of the PPP (1). The treatment covers the chemistry of reactions, enzymes, methods, tissue distributions, and the mathematical theory for the quantitation of metabolism by a theoretical connection of the pathways of Figs. 1 and 2 into a pentose phosphate cycle (PC). 

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