The microbial degradation of cyclohexanecarboxylic acid by a beta-oxidation pathway with simultaneous induction to the utilization of benzoate

The metabolism of cyclohexanecarboxylic acid by a bacterium, designated PRL W19, follows a pathway involving beta-oxidation of coenzyme A intermediates analogous to the classical oxidation of fatty acids. The organism appears to have the property for the constitutive metabolism of caproic acid, and cell extracts contain high levels of the enzymes required for the functioning of the fatty acid cycle. However, the metabolism of cyclohexanecarboxylic acid requires induction by growth or incubation with an appropriate substrate. Extracts of induced cells contain several enzyme activities which are synthesized in response to the induction process. These enzymes include cyclohexanecarboxyl-CoA synthetase, cyclohexanecarboxyl-CoA dehydrogenase, 1-cyclohexenecarboxyl-CoA hydratase, and trans-2-hydroxycyclohexanecarboxyl-CoA dehydrogenase. A characteristics feature of this organism is that it becomes induced for the metabolism of benzoate and catechol during growth on cyclohexanecarboxylic acid, but benzoate does not appear to be an obligatory intermediate in the metabolism of cyclohexanecarboxylic acid.     

Analysis of the electron paramagnetic resonance spectrum of the cobalamin intermediate in ribonucleotide reduction

EPR absorption-derivative lineshapes have been computed and least-squares fitted to the spectrum of the intermediate derived from 5'-deoxy-5'-adenosyl-cobalamin in the ribonucleotide reductase reaction. A Gausian-type intrinsic lineshape was assumed and the effects of inhomogenous broadening, rotation of coordinate axes of the A-tensor relative to the g-tensor, angular dependence of transition probability and ligand hyperfine splitting have also been investigated.When the overall spectrum was computed as the sum of the linshapes corresponding to two distinct Co(II) species, A and B, each having rhombic asymmetry, the least squares procedure converged to a much better fit than with a single species, and matched almost all of the features of the experimental spectrum.The magnetic properties of A and B were compared with those of a series of other Co(II) complexes by a plot of g_|?g₆ versus ∥A₆∥?∥A_|∥. The results eliminate cobalt with 5-coordination to nitrogen for A and B, suggest low-spin cobalt complexes having strongly distorted 6-fold coordination. The possibility that the sixth, symmetry-decreasing ligand is the oxygen molecule is excluded by the chemistry of the system and by the EPR properties of previously reported cob(II)alamins. It is suggested that the sixth ligand is carbonyl, amide or sulfhydryl group of an enzyme sidechain which is inserted off-axis into the coordination position so as to exert the observed symmetry-lowering effect.     

Strychnine poisoning of aquatic birds

Strychnine poisoning was diagnosed in free-flying mallards (Anas platyrhynchos) and a ring-billed gull (Larus delawarensis) found dead on a pond in a zoo. The probable source of toxin was improperly applied strychnine-treated grain used for control of rodents on adjacent farm land. Ingesta of the birds contained 19.7-85.1 mg/kg of strychnine.