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91.
Konka Veeranjaneyulu Denis Charlebois Christophe N. N'soukpoé-Kossi Roger M. Leblanc 《Photosynthesis research》1992,34(2):271-278
Sulfite treatment of pea leaf disks in light caused a significant decrease in the relative quantum yield of photosynthetic oxygen evolution and energy storage (ES) as measured by photoacoustic (PA) spectroscopy. The inhibition was concentration dependent and was less in darkness than in light, indicating light-dependent inhibitory site(s) on the photosynthetic electron transport chain. Further, in darksulfite-treated leaves, the energy storage was more affected than the relative quantum yield of oxygen evolution, suggesting that photophosphorylation and/or cyclic electron transport around PS I are sites of sulfite action in darkness. The Rfd values, the ratio of fluorescence decrease (fd) to the steady-state fluorescence (fs), decreased significantly in leaves treated with sulfite in light but were not affected in dark-treated ones, confirming the photoacoustic observations. Similarly, the ratio of variable fluorescence (Fv) to maximum fluorescence (Fm), a measure of PS II photochemical efficiency, was affected by sulfite treatment in light and not changed by treatment in darkness. An attempt was made to explain the mechanism of sulfite action on photosynthetic electron transport in light and in darkness.Abbreviations APT
amplitude of photothermal signal
- Aox
amplitude of oxygen signal
- ES
energy storage
- fd
fluorescence decrease
- fs
steady-state fluorescence
- Fm
maximum fluorescence
- Fv
variable fluorescence
- PA
photoacoustic(s) 相似文献
92.
James S. Keddie Eira-Wyn Edwards Terry Gibbons Charles H. Shaw Denis J. Murphy 《Plant molecular biology》1992,19(6):1079-1083
Antibodies raised against purified rapeseed 19 kDa oleosin protein were used to screen an embryo-derived gt11 expression library from Brassica napus. A near full-length cDNA clone, BnV, was isolated. The 781 bp cDNA contained an open reading frame of 549 bp followed by an untranslated region of 222 pb and a poly(A) region of 10 bp. Comparisons between this cDNA and a different oleosin cDNA previously isolated from the same library showed high degrees of sequence similarity in the central domain region and in the 3 untranslated region. Sequence similarities between the derived protein sequence of this cDNA and all other known oleosin protein sequences are discussed. 相似文献
93.
94.
Marie-Renée de Roubin Michael D. Cailas Shi-Hsiang Shen Denis Groleau 《Journal of industrial microbiology & biotechnology》1992,9(1):69-72
Summary A central composite design (CCD) was used to evaluate, for the purpose of future process optimization, the influence of pH, yeast extract and ammonium chloride concentrations on the proportion of periplasmic hepatitisB pre-S2 antigen in the recombinant yeastHansenula polymorpha. Each factor was tested at five levels, and a second order polynomial model for the proportion of periplasmic antigen was fitted to the treatment combinations. pH showed the greatest effect: the proportion of periplasmic antigen was greatly increased at the higher pH levels. At the higher pH levels used, the proportion of periplasmic antigen was enhanced by a high concentration of ammonium chloride. Additional experiments have confirmed both the validity of the selected model and the optimal conditions found. A significant correlation was found between the proportion of periplasmic antigen and the total yield of antigen. These results indicated that is should be possible to modulate the distribution of the pre-S2 antigen between the periplasm and the cytoplasm of the yeast. 相似文献
95.
B G Bolscher S W Denis A J Verhoeven D Roos 《The Journal of biological chemistry》1990,265(26):15782-15787
Neutrophil NADPH:O2 oxidoreductase activity, essential in the killing of bacteria by neutrophils, can be elicited in a cell-free system that requires plasma membranes, cytosol and sodium dodecyl sulfate. In addition, GTP or its nonhydrolyzable analog guanosine 5'-3-O-(thio)triphosphate (GTP gamma S) enhances NADPH oxidase activity. We investigated the mechanism of this effect of GTP gamma S in the cell-free system. Cytosol from human neutrophils was separated in three different soluble oxidase components (SOC I, SOC II, and SOC III). Previously we (Bolscher, B. G. J. M., Van Zwieten, R., Kramer, I. J. M., Weening, R. S., Verhoeven, A. J., and Roos, D. (1989) J. Clin. Invest. 83, 757-763) reported that the cytosol contains two components which act synergistically. We now report that one component (previously labeled SOC II) contains two different components that can be separated by ion exchange chromatography. Immunoblotting with antiserum B-1 (Volpp, B. D., Nauseef, W. M., and Clark, R. A. (1988) Science 242, 1295-1297), directed against a cytosolic complex capable of activating latent membranes in the cell-free system, showed a 47-kDa protein in SOC II and a 67-kDa protein in SOC III. SOC II also contains the 47-kDa phosphoprotein, which indicates that this phosphoprotein and the protein recognized by the antiserum are identical. Low rates of NADPH-dependent O2 consumption can be elicited by SOC II and SOC III in the absence of SOC I. This activity is independent of GTP gamma S. Addition of SOC I increases this activity 3-4-fold, only when GTP gamma S is present. Plasma membranes, incubated with SOC I plus GTP gamma S and re-isolated, showed a similar 3-4-fold enhanced O2 consumption with SOC II and SOC III. The GTP gamma S effect is exerted primarily at the level of the plasma membrane. The concentration of GTP gamma S that causes a half-maximal stimulation was 0.4 mu M. It is concluded that SOC I is a functional component of the NADPH oxidase. 相似文献
96.
Cytochrome b5 from Candida tropicalis grown on alkane has been solubilized in three different ways (sodium cholate, trypsin, osmotic wash). After solubilization of the microsomal membrane with sodium cholate, the purification of cytochrome b5 was achieved by DEAE-cellulose chromatography, hydroxylapatite chromatography, a second DEAE-cellulose chromatography and a Sephadex G-75 gel filtration. The purified protein had an apparent molecular weight of 16 000 ± 1 000. After solubilization by trypsin treatment or osmotic wash, the purification procedure yielded a protein with an apparent molecular weight of 12 000 ± 1 000. Though the purified proteins presented molecular weights depending on the technique of solubilization, they exhibited identical optical properties, a great stability with respect to temperature and pH, and were all autooxidable. Redox titrations revealed differences in their midpoint potential values, which were 35 ± 5 mV for the b5 purified after cholate solubilization, —59 ± 5 mV for the b5 purified after trypsin treatment and —65 ± 5 mV for the b5 purified after osmotic wash. 相似文献
97.
Dynorphin in bovine adrenal medulla. II. Isolation, partial characterization and biological activity of two distinct molecules 总被引:3,自引:0,他引:3
Two highly potent dynorphin-like peptides were isolated from bovine adrenal medulla by successive chromatography of an acid (HCl) extract on Sephadex G-10, carboxymethylcellulose, Sephadex G-50 and partition chromatography on Sephadex G-50. Amino acid analysis of both peptides revealed the presence of 24 amino acids including the composition of dynorphin-(1-13) and differing from each other only by a few residues. Both peptides were shown to have the same activity as dynorphin-(1-13) in the guniea pig ileum assay and reacted as well as dynorphin-(1-13) with a specific antibody (R-31) directed against the synthetic material. 相似文献
98.
Pyruvic dehydrogenase activity has been examined in a number of highly purified leaf organelles. In spinach leaf cell, the major activity is in the mitochrondrion with low activity in isolated chloroplasts. The major source of CO2 derived from pyruvic acid metabolism in the isolated chloroplast is via the acetolactic synthase reaction localized in the chloroplast. Evidence is presented that the leaf mitochondrion contains both the pyruvic acid dehydrogenase and an acetyl coenzyme A hydrolase. It is suggested that free acetic acid is generated in the mitochrondrion and then moves to the chloroplast where acetyl coenzyme synthetase converts it from the metabolically inert acid to the very metabolically active acetyl coenzyme A. 相似文献
99.
D. Denis S. Charleson A. Rackham T.R. Jones A.W. Ford-Hutchinson A. Lord M. Cirino Y. Girard M. Larue J. Rokach 《Prostaglandins & other lipid mediators》1982,24(6):801-814
Leukotriene F4 (LTF4 and LTF4 sulfone have been synthesized and their biological activities determined in the guinea pig.
LFT4 displayed comparable activity to LTD4 on guinea pig trachea and parenchyma but was less active on the ileum. When injected intravenously into the guinea pig, LTF4 induced a bronchoconstriction (ED50 16 μg Kg−1) which was blocked by indomethacin and FPL-55712 and was 50–100 X less potent than LTD4 in this assay. LTF4 sulfone was approximately 2–5 times less active than LTF4
and
. When injected into guinea pig skin with PGE2 (100 ng); LTF4 and LTF4 sulfone (10–1000 ng) induced changes in vascular permeability. The order of potency in this assay was LTE4 sulfone = LTD4 = LTD4 sulfone > LTE4 > LTF4 = LTF4 sulfone. 相似文献
100.
M. L. Delorme J. Denis B. Nordlinger M. Boschat P. Opolon 《Journal of neurochemistry》1981,36(3):1058-1066
Experimental acute liver ischemia in pigs induces an increment in plasma free tryptophan with decreased total tryptophan. Brain tryptophan is elevated in all brain areas. A slight, but significant increase of brain serotonin is demonstrated in the striatum only, while 5-HIAA (5-hydroxyindoleacetic acid) is significantly lower in the hypothalamus. Other brain areas do not show significant changes in serotonin and 5-HIAA levels. Neither the high plasma free tryptophan levels, nor the decreased sum of neutral competitive amino acids are consistent with such an elevation of brain tryptophan. Hemodialysis was carried out with two different kinds of membranes: cuprophan (with an efficient removal of molecules up to molecular weight 1300) and AN 69 polyacrylonitrile (efficient removal up to 15,000). Ammonia and aminoacid clearance are similar for both membranes. After AN 69, plasmatic free tryptophan and brain tryptophan are lower than after liver devascularization, but still higher than normal. Serotonin significantly increases in the cortex, midbrain and hypothalamus without concomitant rise of 5-HIAA levels. After cuprophan hemodialysis, plasma total tryptophan is lower than in normal and even comatose animals, whereas free tryptophan is normal. Intracerebral tryptophan is similar to AN 69 dialysed animals, but in the hypothalamus it is similar to nondialysed animals. Brain serotonin levels are not modified. 5-HIAA decreases in the hypothalamus. This finding suggests that middle molecules (which are not cleared out with cuprophan hemodialysis) are involved in the intracerebral transfer of tryptophan and the metabolism of serotonin, mainly in the hypothalamus. 相似文献