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971.
Complementary DNA of cytochrome P-450 CYP1A, in addition to CYP1A1, has been isolated from Japanese eel (Anguilla japonica) liver treated with 3-methylcholanthrene. The cDNA contained a 5′ untranslated region of 66 bp, an open reading frame of
1554 bp coding for 517 amino acids and a stop codon, and a 3′ untranslated region of 1166 bp. The predicted molecular weight
of the Japanese eel CYP1A was approximately 58.5 kDa. The nucleotide sequence exhibited identities with the reported CYP1A1
sequences of 77% for Japanese eel, 75% for rainbow trout, 72% for scup, plaice, and butterfly fish, and 71% for toadfish.
The deduced amino acid sequence exhibited identities with the reported CYP1A1 sequences of 78% for Japanese eel, 77% for rainbow
trout, 75% for scup, 74% for toadfish, 73% for plaice, and 72% for butterfly fish. The novel eel CYP1A obtained had less similarity
to the other teleost CYP1A1 proteins (72%–78%) than that of the eel CYP1A1 (74%–80%). When compared with mammalian CYP proteins,
the novel eel CYP1A was more similar to the CYP1A1 proteins (54%–56%) than to the CYP1A2 proteins (50%–53%). The phylogenetic
tree of the teleost CYP1A genes constructed using the maximum likelihood method suggested that the novel eel CYP1A is ubiquitous among the Anguilliformes.
Received August 25, 2000; accepted November 30, 2000 相似文献
972.
The system of producing long chain dicarboxylic acid (DCA) by Candida tropicalis is an aerobic and viscous fermentation system. A method to overcome the gas-liquid transport resistance and to increase oxygen supply is by adding hydrogen peroxide (H(2)O(2)) to the fermentation system. Here we report that the H(2)O(2) not only can enhance the oxygen supply but also change the metabolism by inducing cytochrome P450, the key enzyme of a, o-oxidation. When C. tropicalis was cultivated in a 3-L bioreactor using the combination of aeration and H(2)O(2) feeding, DCA production rates increased by about 10% after a short period of decrease at the beginning. Furthermore, the experiments showed that the maximum activities of P450 could be induced at 2 mM H(2)O(2), and the inducible mechanisms are also discussed. Moreover, we suggest that alkane might be oxidized through the "peroxide shunt pathway" when H(2)O(2) is present. By adding H(2)O(2), the DCA yield in a 22-L bioreactor could increase by 25.3% and reach 153.9 g/L. 相似文献
973.
Olson JM 《Photosynthesis research》2001,68(2):95-112
I have re-examined my 1970 article ‘Evolution of Photosynthesis’ (Olson JM, Science 168: 438–446) to see whether any of my
original proposals still survive. My original conviction that the evolution of photosynthesis was intimately connected with
the origin of life has been replaced with the realization that photosynthesis may have been invented by the Bacteria after
their divergence from the Archea. The common ancestor of all extant photosynthetic bacteria and cyanobacteria probably contained
bacteriochlorophyll a, rather than chlorophyll a as originally proposed, and may have carried out CO2 fixation instead of photoassimilation. The first electron donors were probably reduced sulfur compounds and later ferrous
iron. The common ancestor of all extant reaction centers was probably similar to the homodimeric RC1 of present-day green
sulfur bacteria (Chlorobiaceae) and heliobacteria. In the common ancestor of proteobacteria and cyanobacteria, the gene for
the primordial RC1 was apparently duplicated and one copy split into two genes, one for RC2 and the other for a chlorophyll
protein similar to CP43 and CP47 in extant cyanobacteria and chloroplasts. Homodimeric RC1 and homodimeric RC2 functioned
in series as in the Z-scheme to deliver electrons from Fe(OH)+ to NADP+, while RC1 and/or RC2 separately drove cyclic electron flow for the production of ATP. In the line of evolution leading to
proteobacteria, RC1 and the chlorophyll protein were lost, but RC2 was retained and became heterodimeric. In the line leading
to cyanobacteria, both RC1 and RC2 replaced bacteriochlorophyll a with chlorophyll a and became heterodimeric. Heterodimeric RC2 further coevolved with a Mn-containing complex to utilize water as the electron
donor for CO2 fixation. The chlorophyll–protein was also retained and evolved into CP43 and CP47. Heliobacteria are the nearest photosynthetic
relatives of cyanobacteria. The branching order of photosynthetic genes appears to be (1) proteobacteria, (2) green bacteria
(Chlorobiaceae plus Chloroflexaceae), and (3) heliobacteria plus cyanobacteria.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
974.
975.
Purified plasma membrane (PM) vesicles from higher plants contain redox proteins with low‐molecular‐mass prosthetic groups such as flavins (both FMN and FAD), hemes, metals (Cu, Fe and Mn), thiol groups and possibly naphthoquinone (vitamin K1), all of which are likely to participate in redox processes. A few enzymes have already been identified: Monodehydroascorbate reductase (EC 1.6.5.4) is firmly bound to the cytosolic surface of the PM where it might be involved in keeping both cytosolic and, together with a b‐type cytochrome, apoplastic ascorbate reduced. A malate dehydrogenase (EC 1.1.1.37) is localized on the inner side of the PM. Several NAD(P)H‐quinone oxidoreductases have been purified from the cytocolic surface of the PM, but their function is still unknown. Different forms of nitrate reductase (EC 1.6.6.1–3) are found attached to, as well as anchored in, the PM where they may act as a nitrate sensor and/or contribute to blue‐light perception, although both functions are speculative. Ferric‐chelate‐reducing enzymes (EC 1.6.99.13) are localized and partially characterized on the inner surface of the PM but they may participate only in the reduction of ferric‐chelates in the cytosol. Very recently a ferric‐chelate‐reducing enzyme containing binding sites for FAD, NADPH and hemes has been identified and suggested to be a trans‐PM protein. This enzyme is involved in the reduction of apoplastic iron prior to uptake of Fe2+ and is induced by iron deficiency. The presence of an NADPH oxidase, similar to the so‐called respiratory burst oxidase in mammals, is still an open question. An auxin‐stimulated and cyanide‐insensitive NADH oxidase (possibly a protein disulphide reductase) has been characterized but its identity is still awaiting independent confirmation. Finally, the only trans‐PM redox protein which has been partially purified from plant PM so far is a high‐potential and ascorbate‐reducible b‐type cytochrome. In co‐operation with vitamin K1 and an NAD(P)H‐quinone oxidoreductase, it may participate in trans‐PM electron transport. 相似文献
976.
Photosynthetic acclimation to reduced growth irradiances (650 and 200 µmol m–2 s–1) in Eleusine coracana (L.) Garten, a nicotinamide adenine dinucleotide-malic enzyme (NAD-ME) C4 species and Gomphrena globosa L., a nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME) C4 species were investigated. E. coracana plants acclimated in 4 and 8 d to 650 and 200 µmol m–2 s–1, respectively, whereas G. globosa plants took 8 and 10 d, respectively, to acclimate to the same irradiances. The acclimation to reduced irradiance was achieved in both species by greater partitioning of chlorophyll towards the light-harvesting antennae at the expense of functional components. However, magnitude of increase in the light-harvesting antenna was higher in E. coracana as compared to G. globosa. Superior photosynthetic acclimation to reduced irradiance in G. globosa was due to the smaller change in functions of the cytochrome b
6/f complex, photosystem (PS) 1 and PS2 leading to the higher carbon fixation rates compared to E. coracana. 相似文献
977.
978.
细胞色素P450基因及其在植物改良中的应用 总被引:6,自引:0,他引:6
细胞色素P450是一类含血红素的氧化还原酶类,它参与多种生化反应,在防御生物免受病虫害及逆境胁迫等方面具有重要作用。生物基因组序列分析表明,它是一个基因超家族。许多细胞色素P450基因已被鉴定和克隆,并应用于植物遗传改良;在转基因培育多抗性植物、创造植物雄性不育系,提高植物降解化学农药残留等污染物的能力和有效生产具有药用价值的化合物等方面已取得可喜进展,显示出广阔的应用前景。
Abstract:Cytochrome P450s are heme-containing mixed-function oxidases,involving in lots of biochemical reactions.They play an important role in preventing plants from pathogen and insect attacks and environmental stress.Sequence analysis of genomes has revealed that P450 is a gene super-family.Many cytochrome P450s have been characterized and cloned.Some of them have been used in plant genetic improvement.A great progress has been made in using these P450 genes to create the transgenic plants with multiple resistances,male sterility,higher capability to dissolve toxic chemicals and pollutants and effective productivity of high valuable compounds,indicating P450 genes have a broad prospect with great potential application. 相似文献
979.
mtDNA中COⅠ分子标记在常见食尸性蝇类鉴定中的应用 总被引:5,自引:1,他引:4
死后不同时间,在尸体上出现不同种类食尸性蝇类的演替规律,可用于准确推断死亡时间。传统上仅依据蝇类形态学特征来判断种属,但由于蝇类的形态结构复杂和种间形态差异微小等特点,对蝇类尤其是对蝇类幼虫的种属鉴别很难。因此应用分子生物学方法对食尸性蝇类及其幼虫进行种属鉴定非常重要。本研究主要是利用此方法对我国西部部分地区常见双翅目食尸性蝇类包括:开普黑蝇、大头金蝇、丝光绿蝇及部分卵,铜绿蝇、棕尾别麻蝇及部分幼虫和蛹的线粒体DNA(mtDNA)上细胞色素氧化酶辅酶Ⅰ(COⅠ)中278 bp的基因序列进行鉴别。除个别蝇类如丝光绿蝇与铜绿蝇外,该方法均能有效地将上述食尸性蝇类鉴定到种属水平。在我国,它将成为法医鉴别食尸性蝇类种属的可靠依据。 相似文献
980.
Role of polyamine metabolism in kainic acid excitotoxicity in organotypic hippocampal slice cultures
Polyamines are ubiquitous cations that are essential for cell growth, regeneration and differentiation. Increases in polyamine metabolism have been implicated in several neuropathological conditions, including excitotoxicity. However, the precise role of polyamines in neuronal degeneration is still unclear. To investigate mechanisms by which polyamines could contribute to excitotoxic neuronal death, the present study examined the role of the polyamine interconversion pathway in kainic acid (KA) neurotoxicity using organotypic hippocampal slice cultures. Treatment of cultures with N1,N(2)-bis(2,3-butadienyl)-1,4-butanediamine (MDL 72527), an irreversible inhibitor of polyamine oxidase, resulted in a partial but significant neuronal protection, especially in CA1 region. In addition, this pre-treatment also attenuated KA-induced increase in levels of lipid peroxidation, cytosolic cytochrome C release and glial cell activation. Furthermore, pre-treatment with a combination of cyclosporin A (an inhibitor of the mitochondrial permeability transition pore) and MDL 72527 resulted in an additive and almost total neuronal protection against KA toxicity, while the combination of MDL 72527 and EUK-134 (a synthetic catalase/superoxide dismutase mimetic) did not provide additive protection. These data strongly suggest that the polyamine interconversion pathway partially contributes to KA-induced neurodegeneration via the production of reactive oxygen species. 相似文献