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ADP/ATP Translocator from Pea Root Plastids (Comparison with Translocators from Spinach Chloroplasts and Pea Leaf Mitochondria) 总被引:6,自引:1,他引:5 下载免费PDF全文
The kinetic properties of the adenosine 5[prime]-diphosphate/adenosine 5[prime]-triphosphate (ADP/ATP) translocator from pea (Pisum sativum L.) root plastids were determined by silicone oil filtering centrifugation and compared with those of spinach (Spinacia oleracea L.) chloroplasts and pea leaf mitochondria. In addition, the ADP/ATP transporting activities from the above organelles were reconstituted into liposomes. The Km(ATP) value of the pea root ADP/ATP translocator was 10 [mu]M and that for ADP was 46 [mu]M. Corresponding values of the spinach ADP/ATP translocator were 25 [mu]M and 28 [mu]M, respectively. Comparable results were obtained for the reconstituted ATP transport activities. The transport was highly specific for ATP and ADP. Adenosine 5[prime]-monophosphate (AMP) caused only a slight inhibition and phosphoenolpyruvate and inorganic pyrophosphate caused no inhibition of ATP uptake. With pea root plastids and spinach chloroplasts, Km values >1 mM were obtained for ADP-glucose. Since the concentrations of ATP and ADP-glucose in the cytosolic compartment of spinach leaves have been determined as 2.5 and 0.6 mM, respectively, a transport of ADP-glucose by the ADP/ATP translocator does not appear to have any physiological significance in vivo. Although both the plastidial and the mitochondrial ADP/ATP translocators were inhibited to some extent by carboxyatractyloside, no immunological cross-reactivity was detected between the plastidial and the mitochondrial proteins. It seems probable that these proteins derive from different ancestors. 相似文献
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To characterize the developmental stage of tomato fruits, chlorophyll
content, photosynthetic O2 evolution and CO2 fixation of pericarp slices
were determined. During the first developmental stages a higher expression
level of the triose phosphate translocator was detected. Transport
measurements revealed that both the hexose phosphate and the triose
phosphate translocator are very likely to be active at this time. Plastidic
and cytosolic fructose-1,6-bisphosphatase are active in green fruit
pericarp, whereas in red pericarp only the cytosolic form is present.
Tomato fruit chloroplasts are able to synthesize starch from Glc6P. Starch
synthesis is strongly dependent on the addition of 3PGA and ATP and on
plastid illumination. Fruit chloroplasts exhibit very low CO2 fixation
rates and so the capacities of green pericarp slices were investigated. In
relation to chlorophyll content, pericarp slices show the same capacity of
starch synthesis as spinach or potato leaves. To investigate the presence
of further reactions consuming the products of photosynthetic electron
transport, the GOGAT activity was measured. In the light,
glutamine/2-oxoglutarate-dependent formation of glutamate occurred with a
high activity. In the presence of Glc6P only 18% of the light activity was
obtained. Since the Glc6P-dependent activity is rather low, the release of
14CO2 from labelled
[1-14C]-Glc6P was also measured. In the dark, the
formation of glutamate and oxidation of Glc6P are very tightly coupled to
each other in fruit chloroplasts. 相似文献
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Monique Benz ;Thomas Bals ;Irene Luise Gugel ;Markus Piotrowski ;Andreas Kuhn ;Danja Schunemann ;Jurgen Soll ;Elisabeth Ankele 《植物生理学报》2009,(6):1410-1424
All members of the YidC/Oxal/Alb3 protein family are evolutionarily conserved and appear to function in membrane protein integration and protein complex stabilization. Here, we report on a second thylakoidal isoform of Alb3, named Alb4. Analysis of Arabidopsis knockout mutant lines shows that AIb4 is required in assembly and/or stability of the CF1CF0-ATP synthase (ATPase). alb4 mutant lines not only have reduced steady-state levels of ATPase subunits, but also their assembly into high-molecular-mass complexes is altered, leading to a reduction of ATP synthesis in the mutants. Moreover, we show that Alb4 but not AIb3 physically interacts with the subunits CF1β and CF0ll. Summarizing, the data indicate that AIb4 functions to stabilize or promote assembly of CF1 during its attachment to the membrane-embedded CF0 part. 相似文献
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Studies of the Enzymic Capacities and Transport Properties of Pea Root Plastids 总被引:12,自引:5,他引:7 下载免费PDF全文
Plastids have been isolated from pea (Pisum sativum L.) roots with a high degree of purity and intactness. In these plastids, the activity of enzymes involved in carbohydrate metabolism have been analyzed and corrected for cytosolic contamination. The results show that fructose-1,6-bisphosphatase, NAD-glyceraldehyde phosphate dehydrogenase, and phosphoglyceromutase are not present in pea root plastids. Transport measurements revealed that inorganic phosphate, dihydroxyacetone phosphate (DHAP), 3-phosphoglycerate, 2-phosphoglycerate, phosphoenolpyruvate, and glucose-6-phosphate (Glc6p) are transported across the envelope in a counterexchange mode. Transport of glucose-1-phosphate was definitely excluded. The oxidation of Glc6P by intact plastids resulted almost exclusively in the formation of DHAP. The parallel measurement of DHAP formation and NO2- consumption during Glc6P-supported nitrite reduction yielded a ratio of NO2-reduced/DHAP formed of 1.6, which is relatively close to the theoretical value of 2.0. These results show that the oxidation of Glc6P, involving the uptake of Glc6P and the release of DHAP, and the reduction of NO2- are very tightly coupled to each other. 相似文献
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Anamélia de Souza Jesus Hugo Eduardo Schunemann Jackson Müller Moira Ansolch da Silva Júlio César Bicca-Marques 《Primates; journal of primatology》2010,51(3):227-230
Hybridization between Alouatta spp. has been suggested at contact zones of A. palliata and A. pigra in Mexico and of A. caraya and A. guariba clamitans in Brazil and Argentina. Whereas genetic data confirmed hybridization between the former pair of species, hybrid individuals
of the latter pair have been putatively identified on the basis of a mosaic pelage color. In this paper, we describe the first
confirmed cases of hybridization between a female A. guariba clamitans and a male A. caraya. One hybrid male was born in 2007 and one hybrid female was born in 2009 with distinct coat colors. The male resembled the
newborn color pattern characteristic of A. guariba clamitans, whereas the female resembled the newborn pattern of A. caraya. The birth and survival of the male hybrid for a year and a half indicated the viability of the heterogametic sex. 相似文献
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