Wood-Werkman reaction

The assimilation of CO2 by bacteria was first demonstrated by Wood and Werkman who observed that during the fermentation of glycerol by propionic acid bacteria there was an over-all uptake of COj and that the amount of product (succinic acid) formed corresponded to the CO which was taken up. Since pyruvic acid was known to be present it was proposed that pyruvic acid condenses with CO to produce oxalacetic acid (Fig. 3, Wood-Werkman reaction) which is subsequently converted to succinic acid. 

In this way Solomon and coworkers attempted to explain the conversion of lactate, pyruvate and carbon dioxide to glycogen. According to the proposed mechanism, carboxyl-labelled pyruvate must first undergo the Wood-Werkman reaction to form oxalacetate before carboxyl-labelled phosphopyruvate can be formed by way of fumarate, phosphomalate and phospho-oxalacetate. This hypothesis is no longer necessary in view of Lardy and Ziegler s results described above. It is possible, however, that both pathways are utilized. 

Carbon dioxide is also fixed in the dark by photosynthetic organisms by the so-called Wood-Werkman reaction (Wood and Stjemholm, 1962). The CO2 assimilated, however, rarely exceeds that formed by dark respiration i.e. there is no net CO2 uptake. On the other hand, the amount of organic carbon derived from CO2 may be as high as 30% in heterotrophic bacteria and 90% in mixotrophic organisms. In the natural environment, non-photo-synthetic CO2 fixation by these organisms, together with the above-mentioned dark fixation by photosynthetic organisms, may under some condi-... 

The decarboxylation of oxalacetic acid was postulated by Wood and Werkman to participate in the fermentation process of Propionobacteria. They postulated that a reversal of this decarboxylation resulted in the fixation of CO2 by these bacteria, and the name, Wood-Werkman reaction, was used to identify this postidated mechanism for the first fixation of CO in carbon chains to be demonstrated in heterotrophic organisms. [C. H. Werkman and H. G. Wood, Advances in Emytnol. 2, 136 (1942).] The fixation of CO in succinate observed by these workers may be explained by the reactions discussed on p. 148. 

PU+COj— OA (Wood-Werkman reaction, possibly followed by production of KG through the tricarboxylic acid cycle) ... 

Phosphate is a necessary component of the reaction system (122). With phosphate-free bicarbonate.saIine there is no amino acid synthesti, or a very small one, unless oatalytio amoimts of dicarboxylic acid ore added. With borate buffer either a dicar-boxylio acid or bicarbonate+phosphate must be added to secure rapid formation of amino-N. These findings indicate the participation of phosphorylation in the Wood-Werkman reaction (cf. 12fla). The further stqM of NHrsynthesia do not require aided phosphate, though this does not preclude intermediary phosphorylations at the expense of free or organic iiUraedlular phosphate. 

For instance, shifts in the equilibria AS+PU AL+OA and GL+PU AL+KQ will be mterdependent with the prevailing trend for liberation of CO from OA, or its fixation in the Wood-Werkman reaction and subsequent stabiliaation as AS (resp. COt fixation in Ochoa s reaction or stabilization of KO, in the form of GL). Only KG, but not OA, is active in catalyzing indirect deamination (p. 24), whereas the observationa of Kritzmann and Melik-Sarkissyan seem to indicate that chieQy OA, rather than KG, is the primary aoaeptor of ammonia in reductive amination. On the other hand, in animal tissues only GL is available for the reversible binding of ammonia as amide, while AS in inactive. 

By 1950 biotin had been implicated in a number of seemingly unrelated enzymatic processes, including (1) the decarboxylation of oxaloacetate and succinate (2) the Wood-Werkman reaction , that is, the /5-carboxylation of pyruvate (3) the biosynthesis of aspartate (4) the biosynthesis of unsaturated fatty acids (5) the deamination of certain amino acids (6) the synthesis of certain biotin-independent enzymes. In each case the enzymatic or metabolic basis for these observations can now be explained in terms of the unequivocally established role of biotin as an enzymatic COg carrier or through indirect effects. 

Wood-Werkman reaction. On close study it became clear that it is possible to obtain oxaloacetate from pyruvate by two different routes. In the first route, activated carbon dioxide is added with the aid of a biotin-containing enzyme ... 

This reaction became known as the Wood and Werkman reaction. Actually, the Wood and Werkman reaction does not occur in the propionic acid bacteria, although, pyruvate carboxylase which does catalyze this reaction but with utilization of ATP, has been found in numerous other tissues and organisms. 

Evidence bearing on this question became available in 1941 from isotope experiments by Wood, Werkman, Hemingway, and Nier, and by Evans and Slotin, working with pigeon liver. The metabolism of this tissue is in many ways similar to that of pigeon muscle, as far as the oxidation of pyruvic acid is concerned, except that liver is capable of performing at least one additional reaction, the synthesis of oxalacetate from pyruvate and carbon dioxide - ... 

Carboxylation. Another reaction of pyruvate closely connected wuth the citrate cycle is the carboxylation to form oxaloacetate. Wood and Werkman discovered it originally as a sum of reactions in microorganisms, and it is often called the... 

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