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Biomedical subjects

J B Mudd

Publications and source records attributed to J B Mudd.

At least 73 records · Page 4Linked to original sources
PubMed1970

The structure and biosynthesis of phosphatidyl inositol in cauliflower inflorescence.

Phosphatidyl inositol has been isolated from cauliflower inflorescence and soybean. Analysis of the fatty acid distribution showed that unsaturated fatty acids were preferred at position 2, and that saturated fatty acids were preferred at position 1.Mitochondrial preparations from cauliflower inflorescence were capable of synthesizing phosphatidyl inositol from myo-inositol and cytidine diphosphate diglyceride. The optimal pH for the reaction was 9.0. Metal ions were required for the reaction: Mn(2+) ions were optimally effective at 1.5 mm, and Mg(2+) ions were maximally effective at 30 mm. The maximal rate in the presence of Mn(2+) was 9 times as great as that in the presence of Mg(2+). Phosphatidyl inositol could also be synthesized when cytidine diphosphate diglyceride was replaced by cytidine triphosphate, but the pH optimum then shifted to 8.1.

Journal Article↗
PubMed1970

Biosynthesis of cytidine diphosphate diglyceride by enzyme preparations from cauliflower.

The activity of the enzyme responsible for the synthesis of cytidine diphosphate diglyceride has been found in the 20,000g pellet of a cauliflower (Brassica oleracea) inflorescence homogenate. Greater enzyme activity was found in the pellet after treatment with 0.02% Triton X-100, or after freezing and thawing. Activity was greater when fluoride was included in the reaction mixture. The enzyme has a pH optimum of 5.6, an optimal Mn(2+) concentration of 1mm and an optimal Mg(2+) concentration of 30 mm. At the optimal concentration, Mn(2+) was 4 times better than Mg(2+). The utilization of biosynthesized cytidine diphosphate diglyceride can be enhanced by addition of inositol, thereby causing the formation of phosphatidyl inositol.

Journal Article↗
PubMed1969

Biosynthesis of galactolipids by enzyme preparations from spinach leaves.

The pH optimum for galactolipid synthesis from UDP-galactose by spinach chloroplasts is 7.2 in Tris-HCl or phosphate buffer. The products include sterol glycosides, trigalactosyl diglyceride (tentatively identified), digalactosyl diglyceride, and monogalactosyl diglyceride in increasing order of quantity. The proportion of monogalactosyl diglyceride decreases and that of digalactosyl diglyceride increases as the pH is lowered. The galactolipid synthesis is quite resistant to elevated temperature; maximal incorporation of galactose from UDP-galactose was observed at 45 degrees C. The proportion of monogalactosyl diglyceride was greater at the higher temperatures. As much as 40% of the galactolipid-synthesizing capability of a spinach leaf homogenate is not sedimented by centrifugation for 60 min at 100,000 g. An acetone powder of spinach chloroplasts contains enzymes which catalyze galactolipid synthesis. This preparation is dependent on added diglycerides in order to make galactolipid, whereas the chloroplast preparation is not dependent on added diglycerides. Molecular species of diglycerides were compared as requirements for galactolipid synthesis. The requirement was satisfied best by the diglycerides of highest unsaturation. Methylation of the free hydroxyl of the diglyceride eliminated the effectiveness.

Chloroplasts↗
PubMed1968

Acetate binding of spinach chloroplasts as a facet of fatty acid synthesis.

A particulate fraction of spinach chloroplasts is the major site of binding when either acetate or acetyl-CoA is used as substrate. The acetate is linked covalently, and the binding is inhibited by reagents which react with sulfhydryl groups. The amount of acetate bound is lowered by both citrate and oxaloacetate; however, the binding is not reversed by oxaloacetate. Reversal of binding is also not brought about by the addition of unlabeled acetyl-CoA. If cofactors for fatty acid synthesis and cold acetyl-CoA are added, the binding of labeled acetate is reversed. Acyl carrier protein from E. coli increases the binding of labeled acetate.

Acetates↗
PubMed1968

Lipid fixation during preparation of chloroplasts for electron microscopy.

Reaction of osmium tetroxide with isolated spinach chloroplasts fixed completely the glycolipids, phosphatidyl glycerol, and phosphatidyl choline. Under the same reaction conditions only 30% of the chlorophyll was fixed. Reaction of potassium permanganate with isolated spinach chloroplasts fixed more than 90% of the glycolipids, phosphatidyl glycerol, and phosphatidyl choline, provided the reaction period was long enough. Potassium permanganate also fixed the chlorophyll. Reaction of osmium tetroxide and potassium permanganate with isolated (14)C-lipids from Chlorella pyrenoidosa fixed 59% and 66% of the radioactivity, respectively. The lipids that were not fixed included sterols and pigments. Electron micrographs show that chloroplasts extracted with chloroform-methanol after fixation in osmium tetroxide or potassium permanganate differ from those dehydrated with acetone mainly in that in the former, osmiophilic globules have been removed and there seems to be some fusion of the boundary membranes and grana membranes. These effects may be due to the extraction of unfixed, neutral lipids such as sterols and quinones.

Chloroplasts↗
PubMed1968

Lipid composition of chloroplasts isolated by aqueous and nonaqueous techniques.

Chloroplasts isolated from tobacco leaves in 0.5 M sucrose solution (the 1000 g pellet) contained 83% of the total cellular monogalactosyl diglyceride, 88% of the digalactosyl diglyceride, 76% of the sulfolipid, and 74% of the phosphatidyl glycerol. Phosphatidyl inositol was concentrated in the 15,000 g pellet. Phosphatidyl choline and phosphatidyl ethanolamine were concentrated in the 15,000 g supernatant fraction. Chloroplasts isolated from tobacco leaves by a nonaqueous technique in hexane-carbon tetrachloride show a glycerolipid composition similar to that found in chloroplasts isolated in the aqueous system, even though some lipid, particularly monogalactosyl diglyceride, is extracted by the organic solvent during the process.

Alkanes↗
PubMed1966

Malaria infection (Plasmodium iophurae): changes in free amino acids.

The course of infection of the avian malaria Plasmodium lophurae in the duckling is characterized by striking increase in the intraerythrocytic free amino acid pool. The quality and quantity of this change result from the presence of the parasite and for the most part reflect the free amino acid pool of the growing plasmodium. No significant changes in the free amino acids in plasma were noted during infection.

Amino Acids↗
PubMed1966

Lipid synthesis in the presence of nitrogenous compounds in Chlorella pyrenoidosa.

Acetate was incorporated by Chlorella pyrenoidosa into nonvolatile water-soluble compounds (amino acids, organic acids and carbohydrates) with pH optimum between 4 and 5. Incorporation into lipid was maximal at pH 7.5. The proportion of incorporated acetate in lipid was not significantly affected by acetate concentration and chlorophyll concentration in the ranges tested. Illumination of Chlorella during acetate metabolism increased the synthesis of lipid with concomitant decrease in the synthesis of water-soluble compounds. Nitrate and ammonium ions had essentially no effect on acetate metabolism. Inhibition by nitrite was greater on the synthesis of lipid. Illumination reversed the gross inhibition by nitrite, but altered the distribution of incorporated label in favor of the water-soluble compounds.

Eukaryota↗