Ribulose diphosphate oxygenase. V. Presence in ribulose diphosphate carboxylase from Rhodospirillum rubrum

Effect of endocrine disruptor nonylphenol on physiologic features and proteome during growth in Arabidopsis thaliana

We studied the effects of nonylphenol (NP) on physiological features and proteome of Arabidopsis (Arabidopsis thaliana) during growth. Shoot biomass, root biomass and root length were decreased after 10d of NP treatment, especially in high NP concentration treatment (10 and 50 mg L(-1)). Levels of chlorophyll decreased but proline increased in leaves. NP caused oxidative stress; malondialdehyde content was increased with NP treatment, and the activities of ascorbate peroxidase, catalase, CuZnSOD and MnSOD were induced in leaves. The proteome of leaf tissue was analyzed by 2-D gel electrophoresis and mass spectrometry. NP might adversely affect the CO2 assimilation, signal transduction, the endomembrane system and photosynthetic oxygen evolution. NP affects the proteome and physiologic and morphological features of A. thaliana during growth at the concentration can be observed in the environment. Because plants might be exposed to NP for a long time in the surroundings, more attention needs to be paid to the effect of NP on plants.

Molecular and cellular regulation of autotrophic carbon dioxide fixation in microorganisms

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The effects of bivalent cations on ribulose bisphosphate carboxylase/oxygenase

The half-saturation constants for binding of the bivalent cations (Mg2+, Ni2+, Co2+, Fe2+ and Mn2+) to ribulose bisphosphate carboxylase/oxygenase from Glycine max and Rhodospirillum rubrum were measured. The values obtained were dependent on the enzyme and the cation present, but were the same for both oxygenase and carboxylase activities. Ribulose bisphosphate rather than its cation complex was the true substrate. The kinetic parameters Vmax.(CO2), Vmax.(O2), Km(CO2), Km(O2), and K1(O2) were determined for both enzymes and each cation activator. The evolutionary and mechanistic implications of these data are discussed.

Isolation, characterization, and crystallization of ribulosebisphosphate carboxylase from autotrophically grown Rhodospirillum rubrum

Serial culture of Rhodospirillum rubrum with 2% CO2 in H2 as the exclusive carbon source resulted in a rather large fraction of the soluble protein (greater than 40%) being comprised of ribulosebisphosphate carboxylase (about sixfold higher than the highest value previously reported). Isolation of the enzyme from these cells revealed that it has physical and kinetic properties similar to those previously described for the enzyme derived from cells grown on butyrate. Notably, the small subunit (which is a constituent of the carboxylase from eucaryotes and most procaryotes) was absent in the enzyme from autotrophically grown R. rubrum. Edman degradation of the purified enzyme revealed that the NH2 terminus is free (in contrast to the catalytic subunit of the carboxylase from eucaryotes) and that the NH2-terminal sequence is Met-Asp-Gln-Ser-Ser-Arg-Tyr-Val-Asn-Leu-Ala-Leu-Lys-Glu-Glu-Asp-Leu-Ile-Ala-Gly-Gly-Glx-His-Val-Leu-. Crystals of the enzyme were readily obtained by dialysis against distilled water.

Evolution of C4 photosynthesis in response to changes in carbon and oxygen concentrations in the atmosphere through time

The hypothesis is presented that C4 photosynthesis has evolved at lease in part in response to reduced efficiency of C3 photosynthesis due to increased oxygen partial pressures in our recent atmosphere. Oxygen competition with carbon dioxide for the active site on ribulose diphosphate carboxylase was of little consequence when atmospheric levels of CO2 were high and those of O2 were low. However at the present low CO2 and high O2 partial pressures, adaptations for protecting the enzyme from oxygen have been selected.

Enzymes of glycollate formation and oxidation in two members of the rhodospirillacae (purple non-sulphur bacteria)

1. Phototrophic cultures of Rhodomicrobium vanielii do not excrete glycollate when gassed anaerobically with nitrogen plus carbon dioxide, although the addition of alpha-hydroxy-2-pyridine methanesulphonate (HPMS) results in the excretion of a trace amount of glycollate. The inclucion of low amounts of oxygen in this gas mixture results in marked glycollate excretion, higher rates occurring in the presence of HPMS. 2. Cell extracts of Rhodomicrobium vannielii, and also of Rhodospirillum rubrum, which excretes glycollate only under aerobic conditions in the light, catalyze the formation of glycollate from phosphoglycollate and also the oxidation of glycollate to glyoxylate.