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1.  Control of arginine metabolism in Neurospora: flux through the biosynthetic pathway. 
Journal of Bacteriology  1980;141(1):227-234.
The flux into the arginine biosynthetic pathway of Neurospora crassa was investigated using a mutant strain lacking the ornithine-degrading enzyme ornithine aminotransferase (EC 2.6.1.13). Flux was measured by the increase in the sum of the radioactivity (derived from [14C]glutamic acid) in the ornithine pool, the arginine pool, and arginine incorporated into proteins. Complete cessation of flux occurred immediately upon the addition of arginine to the growth medium. This response occurred prior to expansion of the arginine pool. After short-term exposure to arginine (80 min), flux resumed quickly upon exhaustion of arginine from the medium. This took place despite the presence of an expanded arginine pool. Initiation of flux required approximately 80 min when the mycelia were grown in arginine-supplemented medium for several generations before exhaustion of the exogenous arginine. The arginine pool of such mycelia was similar to that found in mycelia exposed to exogenous arginine for only 80 min. The results are consistent with rapid onset and release of feedback inhibiton of arginine biosynthesis in response to brief exposure to exogenous arginine. The insensitivity of flux to the size of the arginine pool is consistent with a role for compartmentation in this regulatory process. The lag in initiation of flux after long-term growth in the presence of exogenous arginine suggests the existence of an additional regulatory mechanism(s). Several possibilities are discussed.
PMCID: PMC293569  PMID: 6444407
2.  Genetic evidence for a common enzyme catalyzing the second step in the degradation of proline and hydroxyproline. 
Journal of Clinical Investigation  1979;64(5):1365-1370.
The initial step in the degradation pathways of proline and hydroxyproline is catalyzed by proline oxidase and hydroxyproline oxidase, yielding delta 1-pyrroline-5-carboxylate and delta 1-pyrroline-3-hydroxy-5-carboxylate, respectively. The second step is the oxidation of delta 1-pyrroline-5-carboxylate to glutamate and delta 1-pyrroline-3-hydroxy-5-carboxylate to gamma-hydroxy-glutamate. To determine if this second step in the degradation of proline and hydroxyproline is catalyzed by a common or by separate enzyme(s), we developed a radioisotopic assay for delta 1-pyrroline-3-hydroxy-5-carboxylate dehydrogenase activity. We then compared delta1-pyrroline-3-hydroxy-5-carboxylate dehydrogenase activity with that of delta 1-pyrroline-5-carboxylate dehydrogenase in fibroblasts and leukocytes from type II hyperprolinemia patients, heterozygotes, and controls. We found that cells from type II hyperprolinemia patients were deficient in both dehydrogenase activities. Furthermore, these activities were highly correlated over the range found in the normals, heterozygotes, and patients. We conclude from these data that a common delta 1-pyrroline-5-carboxylate dehydrogenase catalyzes the oxidation of both delta 1-pyrroline-5-carboxylate and delta 1-pyrroline-3-hydroxy-5-carboxylate, and that this activity is deficient in type II hyperprolinemia.
PMCID: PMC371284  PMID: 500817
4.  Type II hyperprolinemia. Delta1-pyrroline-5-carboxylic acid dehydrogenase deficiency in cultured skin fibroblasts and circulating lymphocytes. 
Journal of Clinical Investigation  1976;58(3):598-603.
Type II hyperprolinemia is an inherited abnormality in amino acid metabolism characterized by elevated plasma proline concentrations, iminoglycinuria, and the urinary excretion of delta1-pyrroline compounds. To define the enzymologic defect of this biochemical disorder, we developed a specific, sensitive radioisotopic assay for the proline degradative enzyme delta1-pyrroline-5-carboxylic acid dehydrogenase. Using this assay, we have shown an absence of delta1-pyrroline-5-carboxylic acid dehydrogenase activity in the cultured fibroblasts from three patients with type II hyperprolinemia. We confirmed this result on cultured cells by demonstrating a similar absence of delta1-pyrroline-5-carboxylic acid dehydrogenase activity in extracts prepared from the peripheral leukocytes of these patients. Additionally, we found significantly decreased levels of delta1-pyrroline-5-carboxylic acid dehydrogenase activity in the leukocyte extracts from five obligate heterozygotes for type II hyperprolinemia. We also demonstrated a reduction in leukocyte delta1-pyrroline-5-carboxylic acid dehydrogenase activity in three successive generations of a family. These results prove that an absence of delta1-pyrroline-5-carboxylic acid dehydrogenase is the enzymologic defect in type II hyperprolinemia and that this defect is inherited in an autosomal recessive fashion.
PMCID: PMC333218  PMID: 956388
5.  Treatment of homocystinuria. 
Archives of Disease in Childhood  1967;42(225):514-520.
PMCID: PMC2019813  PMID: 6061292
6.  Catarrhal Child 
British Medical Journal  1956;1(4971):861.
PMCID: PMC1979525

Results 1-6 (6)