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Biomedical subjects

R E McCarty

Publications and source records attributed to R E McCarty.

At least 91 records · Page 5Linked to original sources
PubMed1974

The role of galactolipids in spinach chloroplast lamellar membranes: I. Partial purification of a bean leaf galactolipid lipase and its action on subchloroplast particles.

A galactolipid lipase has been isolated and partially purified from the chloroplast fraction of the primary leaves of Phaseolus vulgaris var. Kentucky Wonder. The lipase hydrolyzed monogalactosyl diglyceride rapidly and phosphatidyl choline relatively slowly. Triolein and p-nitrophenyl stearate were not hydrolyzed.Spinach subchloroplast particles were excellent substrates for the lipase. Initial rates of fatty acid release from subchloroplast particles at 30 C by the lipase as high as 60 microequivalents per minute per milligram protein were observed. At completion of the reaction, about 2.7 microequivalents of fatty acid were liberated per milligram of chlorophyll in the subchloroplast particles, indicating that major amounts of lipid in the particles were rapidly attacked by the lipase.The treatment of subchloroplast particles with the lipase resulted in a rapid inhibition of light-dependent electron flow. This inhibition was largely prevented when the incubation was carried out in the presence of high concentrations of defatted bovine serum albumin. These results suggest that when precautions are taken to prevent the binding of fatty acids to the subchloroplast particles, large amounts of lipid may be removed without a marked effect on electron flow.

Journal Article↗
PubMed1971

Effects of adenine nucleotides on hydrogen-ion transport in chloroplasts.

1-10 muM ATP stimulated H(+) uptake and slowed the release of H(+) in the dark in chloroplasts illuminated at pH values at which photophosphorylation can occur, but not at pH 6.5. This ATP stimulation of H(+) uptake was abolished by an antiserum to the chloroplast coupling factor and was reduced by the energy transfer inhibitors phlorizin and Dio-9. ATP synthesis after illumination was also enhanced by ATP. Electron flow from water to methyl viologen was inhibited by the same low concentrations of ATP.ADP also increased the extent of H(+) uptake in chloroplasts, even in the presence of arsenate and MgCl(2). In the presence of hexokinase and glucose, as well as arsenate and Mg(++), ADP inhibited H(+) uptake. The failure of previous investigators to observe a direct inhibition of H(+) uptake by phosphorylation was probably caused by a masking of the inhibition by the stimulation of H(+) uptake by ATP. Furthermore, the stimulation of H(+) uptake by ATP provides an explanation for its inhibition of electron flow.

Adenosine Diphosphate↗