Mesaconate citramalate

Consistent with the previous experimental studies [4, 25], the analysis shows the presence of citric acid along with itaconic, citraconic, mesaconic, citramalic, as well as paraconic acid (Figure 9). In addition to these components methyl succinic and hydroaconitic acids show a dominant presence. The presence of these saturated compounds indicates that water reacted with the steel gasket to produce significant H2 the stainless steel gasket is likely to provide an excellent surface site for catalytic hydrogenation. Although the sample was initially shielded... 

S. Except for oxido-reductases, transferases, and hydrolases, most ligases (enzymes that catalyze bond formation) are entirely substrate specific. Thus, fumarate hydratase (or fumarase) reversibly and stereospecifically adds water to fumaric acid to produce (S)-( — )-malic acid only (8) (Figure 1), and another enzyme, mesaconase, adds water to mesaconic acid to form (+ )-citramalic acid (9) (Figure 2). Although no extensive studies are available, it appears that neither fumarase nor mesaconase will add water stereospecifically to any other a,(3-unsaturated acid. 

S)-Citramalic acid (also shown below as 1029), the a-methyl analog of ( S)-malic acid, has been isolated from a variety of natural sources. It can be produced microbially by incubation of mesaconic acid with an extract from Clostridium tetanomorphum cells [220]. 

Fig. 1. Path of glutamate fermentation by Cl. tetanomorphum. The two reactions involved in the interconversion of glutamate to mesaconate are readily isolated from the subsequent reactions by the addition of oipyridyl which inhibits the Fe +-dependent conversion of mesaconate to citramalate. The latter reaction is also strongly inhibited by Og.

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