The stroma of spinach chloroplasts contains ascorbic acid and glutathione at millimolar concentrations. [Reduced glutathione]/[oxidized glutathione] and [ascorbate]/[dehydroascorbate] ratios are high under both light and dark conditions and no evidence for a role of oxidized glutathione or dehydroascorbate in the dark-deactivation of fructose bisphosphatase could be obtained. Addition of H2O2 t...

We report fluorescence lifetimes for in vivo chlorophyll a using a time-correlated single-photon counting technique with tunable dye laser excitation. The fluorescence decay of dark-adapted chlorella is almost exponential with a lifetime of 490 ps, which is independent of excitation from 570 nm to 640 nm. Chloroplasts show a two-component decay of 410 ps and approximately 1.4 ns, the proportion...

Intact (class-A) granal and agranal maize chloroplasts and chloroplast fragments were examined for differential scattering of circularly polarized light (measured at 90 degrees) and c.d. (circular dichroism) (measured at 0 degrees) by using a modified spectropolarimeter with a large acceptance angle. Useful c.d. information was obtained by making corrections for scattered light. Chloroplast fra...

The photoreduction of cytochrome c by spinach chloroplasts has been noted by several investigators (12, 20, 25). In a preliminary report, we have presented evidence that aqueous digitonin extracts of spinach chloroplasts contain a cytochrome c photooxidase (22) which appears to be similar to the photooxidase present in extracts of photosynthetic bacteria studied by Kamen and Vernon (13, 14, 32)...

Acetate concentration in spinach (Spinacia oleracea L.) leaf tissue has been determined by direct measurement in a leaf extract to oe 70 |xm or less. Additional evidence for such low acetate levels came from isotope dilution experiments where the [ l 14C]acetate incorporation into fatty acids was assayed using purified chloroplasts in the presence o f tissue extracts. Pyruvate dehydrogenase com...

The second enzyme of phosphatidic acid synthesis from glycerol-3-phosphate, 1-acylglycerophospate acyltransferase, was localized to the inner envelope membrane of pea chloroplasts. The activity of this enzyme was measured by both a coupled enzyme assay and a direct enzyme assay. Using the coupled enzyme assay, phosphatidic acid phosphatase was also localized to the inner envelope membrane, alth...

During the past decade it has become clear that in cells of higher organisms most protein synthesis is mediated by polysomes occurring free in the cytoplasm or attached to the endoplasmic reticulum. There is ample evidence, however, that synthesis of proteins may also occur at other loci within the cell ; for example, in mitochondria (1-3), in chloroplasts (4-6), and in the nucleus (7-11) . Pro...