PubMed Health⌕ Search

Biomedical subjects

G D Hegeman

Publications and source records attributed to G D Hegeman.

38 records · Page 3Linked to original sources
PubMed1966

Synthesis of the enzymes of the mandelate pathway by Pseudomonas putida. II. Isolation and properties of blocked mutants.

Hegeman, G. D. (University of California, Berkeley). Synthesis of the enzymes of the mandelate pathway by Pseudomonas putida. II. Isolation and properties of blocked mutants. J. Bacteriol. 91:1155-1160. 1966.-Mutants of Pseudomonas putida blocked in early reactions of the pathway for oxidation of d-mandelate were isolated and partially characterized. The specific genetic lesions in these mutants made normal inducer-metabolites of the pathway nonmetabolizable. Under the conditions of gratuitous enzyme synthesis so obtained, it could be shown that the d and l isomers of mandelate are equipotent inducers, and that the synthesis of the first five enzymes of the mandelate pathway is coordinate. Further experiments with the blocked mutants showed that benzoylformate, the third intermediate of the pathway, acts as an inducer without prior conversion to mandelate, and that there is no inducible, concentrating permease for mandelate.

Carboxy-Lyases↗
PubMed1966

Synthesis of the enzymes of the mandelate pathway by Pseudomonas putida. 3. Isolation and properties of constitutive mutants.

Hegeman, G. D. (University of California, Berkeley). Synthesis of the enzymes of the mandelate pathway by Pseudomonas putida. III. Isolation and properties of constitutive mutants. J. Bacteriol. 91:1161-1167. 1966.-Mutants of Pseudomonas putida constitutive for the synthesis of l(+)-mandelate dehydrogenase were obtained after mandelate- or benzoylformate-limited growth in a chemostat. When grown in media noninducing for the wild type, the mutants are capable of coordinate, constitutive synthesis of the first five enzymes of the mandelate pathway. Later enzymes of the pathway that were examined are normally repressed. The constitutive mutants have two other noteworthy properties: they are superinducible by some compounds which induce the mandelate group enzymes in the wild type, or as a result of exhaustion of the carbon and energy source of the medium in which they are grown; and they exhibit a decreased specificity of induction, being inducible by a wide range of compounds devoid of inductive function for the wild type. These results, together with other evidence indicating that the five mandelate group enzymes comprise a regulatory unit, are discussed and evaluated in the context of the general problem of the regulation of complex dissimilatory pathways.

Carboxy-Lyases↗