The Pathway of myo-Inositol Degradation in Aerobacter aerogenes

The structure of the first noncyclic intermediate in the catabolism of myo-inositol by Aerobacter aerogenes has been elucidated. This compound had been thought to be a 4-deoxy-5-ketohexonic acid. However, a reinvestigation of its structure showed it to be a 2-deoxy-5-ketohexonic acid. The phenylosazone derivative was prepared and purified to chromatographic homogeneity as the sodium salt. Periodate oxidation of the osazone generated two products. One was identified chromatographically and colorimetrically as malonic semialdehyde. The other was shown to be identical with the 1,2-bisphenylhydrazone of mesoxaldehyde. These results implied the presence of a methylene at C-2 and a carbonyl at C-5 in the parent compound. A compound identical with the intermediate in inositol catabolism was generated by the action of Acetobacter suboxydans ATCC 621 on 2-deoxy-d-glucose. This result confirmed the presence of a methylene group at position 2 in the inositol intermediate and furthermore made it highly likely that the intermediate is 2-deoxy-5-keto-d-gluconic acid (2-deoxy-d-threo-5-hexulosonic acid).