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S Jackowski

Publications and source records attributed to S Jackowski.

80 records · Page 5Linked to original sources
PubMed1982

Genetic and biochemical analyses of pantothenate biosynthesis in Escherichia coli and Salmonella typhimurium.

Pantothenate (pan) auxotrophs of Escherichia coli K-12 and Salmonella typhimurium LT2 were characterized by enzymatic and genetic analyses. The panB mutants of both organisms and the pan-6 ("panA") mutant of S. typhimurium are deficient in ketopantoate hydroxymethyltransferase, whereas the panC mutants lack pantothenate synthetase. panD mutants of E. coli K-12 were previously shown to be deficient in aspartate 1-decarboxylase. All mutants showed only a single enzyme defect. The finding that the pan-6 mutant was deficient in ketopantoate hydroxymethyltransferase indicates that the genetic lesion is a panB allele. The pan-6 mutant therefore is deficient in the utilization of alpha-ketoisovalerate rather than the synthesis of alpha-ketoisovalerate, as originally proposed. The order of the pan genes of E. coli K-12 was determined by phage P1-mediated three-factor crosses. The clockwise order was found to be aceF panB panD panC tonA on the genetic map of E. coli K-12. The three-factor crosses were greatly facilitated by use of a closely linked Tn10 transposon as the outside marker. We also found that supplementation of E. coli K-12 auxotrophs with a high concentration of pantothenate or beta-alanine increased the intracellular coenzyme A level two- to threefold above the normal level. Supplementation with pantoate or ketopantoate resulted in smaller increases.

Carboxy-Lyases↗
PubMed1981

Regulation of coenzyme A biosynthesis.

Coenzyme A (CoA) and acyl carrier protein are two cofactors in fatty acid metabolism, and both possess a 4'-phosphopantetheine moiety that is metabolically derived from the vitamin pantothenate. We studied the regulation of the metabolic pathway that gives rise to these two cofactors in an Escherichia coli beta-alanine auxotroph, strain SJ16. Identification and quantitation of the intracellular and extracellular beta-alanine-derived metabolites from cells grown on increasing beta-alanine concentrations were performed. The intracellular content of acyl carrier protein was relatively insensitive to beta-alanine input, whereas the CoA content increased as a function of external beta-alanine concentration, reaching a maximum at 8 microM beta-alanine. Further increase in the beta-alanine concentration led to the excretion of pantothenate into the medium. Comparing the amount of pantothenate found outside the cell to the level of intracellular metabolites demonstrates that E. coli is capable of producing 15-fold more pantoic acid than is required to maintain the intracellular CoA content. Therefore, the supply of pantoic acid is not a limiting factor in CoA biosynthesis. Wild-type cells also excreted pantothenate into the medium, showing that the beta-alanine supply is also not rate limiting in CoA biogenesis. Taken together, the results point to pantothenate kinase as the primary enzymatic step that regulates the CoA content of E. coli.

Acyl Carrier Protein↗
PubMed1980

Glycerol permeabilities of fertilized and infertilized mouse ova.

The coefficients of permeability to glycerol, Pglyc, and their temperature-dependence were determined from volume changes of fertilized and unfertilized mouse ova under hyperosmotic conditions. Fertilization caused a significant increase in the value of Pglyc. Unfertilized ova exhibited Pglyc values of 1 X 10(-5), 2 X 10(-6), and 5 X 10(-7) cm/min at approximately 20 degrees C, and approximately 12 degrees C, and approximately 3 degrees C, respectively. Fertilized ova exhibited Pglyc values of 3.4 X 10(-5), 1.3 X 10(-5), and 4.7 X 10(-6) cm/min at apoproximately 20 degrees C, 12 degrees C, and approximately 3 degrees C, respectively. The activation energy of glycerol permeation into fertilized and unfertilized ova was calculated to be 18.7 and 28.4 kcal/mol, respectively. Fertilization caused a rather dramatic increase in glycerol permeability, the major extent of which occurred within about 3 hours after fertilization. Pglyc was also measured at approximately 20 degrees C by isotope uptake. Glycerol uptake calculated indirectly from the volume changes of the ova agreed well with that measured directly by labeled glycerol uptake. It was also found that the zona pellucida fertilized and unfertilized ova did not detectably impede the permeation by glycerol.

Animals↗
PubMed1979

A Ca2+-stimulated ATPase activity in rabbit neutrophil membranes.

An ATPase activity specifically stimulated by micromolar Ca2+ concentrations has been identified in association with rabbit neurophil membranes. These studies provide the basis of further characterization of the Ca2+-ATPase activity with regard to neutrophil function.

Animals↗
PubMed1979

Adenylate cyclase and ATPase activities in red cell membranes of patients and genetic carriers of Duchenne muscular dystrophy.

Basal adenylate cyclase activity was increased in red cell ghosts from both patients with Duchenne muscular dystrophy and their mothers when the activities were compared to proper age-matched controls. The activity of ATPase measured in the presence of Na+, K+, and Mg2+ was not found to be different in erythrocyte ghosts from Duchenne dystrophic patients, age-matched controls, or the mothers of Duchenne patients, and ouabain inhibited ATPase in ghosts to the same extent in all membrane preparations.

Adenosine Triphosphatases↗