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cDNA Clones for Corn Leaf NADH:Nitrate Reductase and Chloroplast NAD(P):Glyceraldehyde-3-Phosphate Dehydrogenase : Characterization of the Clones and Analysis of the Expression of the Genes in Leaves as Influenced by Nitrate in the Light and Dark 总被引:6,自引:3,他引:3 下载免费PDF全文
cDNA clones were selected from a corn (Zea mays L.) leaf lambda gt11 expression library using polyclonal antibodies for corn leaf NADH:nitrate reductase. One clone, Zmnrl, had a 2.1 kilobase insert, which hybridized to a 3.2 kilobase mRNA. The deduced amino acid sequence of Zmnrl was nearly identical to peptide sequences of corn leaf NADH:nitrate reductase. Another clone, Zm6, had an insert of 1.4 kilobase, which hybridized to a 1.4 kilobase mRNA, and its sequence coded for chloroplastic NAD(P)+:glyceraldehyde-3-phosphate dehydrogenase based on comparisons to sequences of this enzyme from tobacco and corn. When nitrate was supplied to N-starved, etiolated corn plants, nitrate reductase, and glyceraldehyde-3-phosphate dehydrogenase mRNA levels in leaves increased in parallel. When green leaves were treated with nitrate, only nitrate reductase mRNA levels were increased. Nitrate is a specific inducer of nitrate reductase in green leaves, but appears to have a more general effect in etiolated leaves. In the dark, nitrate induced nitrate reductase expression in both etiolated and green leaves, indicating light and functional chloroplast were not required for enzyme expression. 相似文献
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Phytochrome-mediated light regulation of nitrate reductase expression in squash cotyledons 总被引:12,自引:3,他引:9 下载免费PDF全文
In etiolated squash (Cucurbita maxima L.) cotyledons, nitrate-inducible NADH:nitrate reductase activity and protein were increased in darkness by red light pulses with red/far-red photoreversibility. Continuous far-red light also led to increased levels of nitrate reductase activity and protein. Poly(A)+RNA, which hybridizes to squash nitrate reductase cDNA, was also increased by light treatments. Thus, we found that after nitrate triggering, nitrate reductase expression appears to be regulated by light via phytochrome. 相似文献
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Plasminogen activator secreted by lymphosarcoma (ascites) of mice was purified up to 163-fold by ammonium sulphate fractionation
at 35% saturation and chromatography on p-aminobenzamidine-Sepharose 4B. The purified activator contained specific activity
of 9980 IU/mg. The plasminogen activator displayed homogeneity by polyacrylamide slab gel electrophoresis and high performance
liquid chromatography. The activator consisted of a single polypeptide chain with an apparent molecular weight of 66,000 daltons
as determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis under reducing conditions as well as gel filtration
on Sephadex G-100. Distinct differences between this activator and urokinase were discernible in respect of specific activities,
fibrin affinity and immunochemical properties. The lymphosarcoma activator appears to be of tissue-type origin since it showed
gross similarity to standard tissue plasminogen activator in terms of modes of binding to fibrin and immunological attributes. 相似文献