muramic acid (C-7, C-8 and C-9) in preference to the pyranose ring (C-I to C-6) when the incubation medium contained non-radioactive glucose. With the 03 compounds the identity of the carbon atoms was maintained, i.e. C-1-+ C-7; C-2-+ C-8; C-3-* C-9. 4. Experiments with the above-named tracers and non-radioactive competitors suggest that phosphoenolpyruvate is the most likely immediate precursor of the side chain of muramic acid. It is not possible, however, completely to exclude any of the compounds involved in glucose degradation by the glycolytic pathway between triose phosphate and phosphoenolpyruvate.

Acetyl 92 ated as described by Hurd7 was introduced into the acid maintaining the temperature at -15 to -10°. The reaction mixture was then fractionated in vacuum.Yields obtained were less than 10%. Acetic anhydride was always formed in substantial amounts due to disproportionation of mixed anhydride.Reaction of Sulfonic Acid Anhydrides with Anhydrous Hydrogen Fluoride.-Sulfonic acid anhydride (1.0 mole) was mixed (Teflon-coated magnetic stirrer) with 30 g. (1.5 moles) of anhydrous hydrogen fluoride at -10°in a fused silica or polyolefin reaction flask. The reaction mixture, protected in the usual way from atmospheric moisture, was stirred for 2 hr. at 0°under a silica or plastic reflux condenser.

The synthesis, characteristics and chemical behaviour of some 3,3‐disubstituted‐2‐ethoxy‐ and 2‐ethy lthio‐1‐azetines, the first examples of a new class of heterocyclic compounds, are described.

No abstract

1. Hydroxyoxoglutarate was obtained by three methods: decarboxylation of oxalomalic acid, and synthesis from glyoxylate and pyruvate by using either Mg(2+) or an enzyme from rat liver as catalysts. 2. The inhibitory effects of oxalomalate and hydroxyoxoglutarate upon aconitate hydratase, isocitrate dehydrogenase (NADP) and oxoglutarate dehydrogenase were investigated. 3. Oxalomalate at low concentrations (1mm) inhibited almost completely both aconitate hydratase and isocitrate dehydrogenase. Hydroxyoxoglutarate also inhibited these enzymes, but at concentrations approximately tenfold that of oxalomalate. 4. Oxalomalate and hydroxyoxoglutarate, at the higher concentrations, inhibited oxoglutarate dehydrogenase to approximately the same extent. 5. It is suggested that the ability of glyoxylate to control reaction rates in the tricarboxylic acid cycle must in some degree be due to its condensation with oxaloacetate and pyruvate to form enzyme inhibitors.