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排序方式: 共有407条查询结果,搜索用时 25 毫秒
1.
Noriaki Murakami Yoshiyuki Tanaka Kunio Takishima Yuzo Minobe Makoto Matsuoka Sei-Ichiro Kiyota Shin-ichi Hatanaka Katsuhiro Sakano 《Journal of plant research》1990,103(4):419-434
We isolated the small subunit of ribulose-1, 5-bisphosphate carboxylase/oxygenase (RuBisCO SSu) from a fern,Asplenium cataractarum and determined its 34 N-terminal amino acid sequence. We obtained a cDNA clone that contains the entire coding region of
the SSu from the same fern species, using synthetic oligonucleotide probes derived from the above amino acid sequence. It
contains a 525 bp open reading frame capable of coding for a polypeptide with 174 amino acids, 31 bp 5′-and 206 bp 3′-noncoding
regions. It was also elucidated that the precursor to the SSu contains a transit peptide of 53 amino acid residues and a mature
protein of 121 residues. We compared the deduced amino acid sequence of the fern SSu with those of 11 other vascular plant
species (including gymnosperms, monocots and dicots). As low as 55% homology was observed between those of a fern and seed
plants. Constancy of the amino acid substitution rate in RuBisCO SSu was supported by our relative rate test. Amino acid substitution
rate per year per site for RuBisCO SSu was calculated to be 0.81×10−9 assuming that the separation between pteridophytes and seed plants arose 380 million years ago. 相似文献
2.
Nobuo Kato Sumiko Mizuno Yukio Imada Masayuki Shimao Chikahiro Sakazawa 《Applied microbiology and biotechnology》1988,27(5-6):567-571
Summary Formaldehyde dismutase was greatly stabilized by immobilization in a urethane prepolymer (PU-6). The immobilized enzyme exhibited stochiometrical dismutation of formaldehyde to methanol and formate in several repeated reactions. Conversion of methanol to formate occurred in a reaction with an immobilized enzyme system consisting of alcohol oxidase, catalase and formaldehyde dismutase, and with an intact cell-mixture of Hansenula polymorpha and Pseudomonas putida. Furthermore, the stability of the cell-mixture during repeated reactions was greatly improved by the immobilization, the 600 mM methanol added periodically being converted to formate in a 75% yield in 12 h. The immobilized cellsystem was also effective for the conversion of several aliphatic alcohols, C1 to C4, to the corresponding acids. 相似文献
3.
The pathogenesis of type E botulism is discussed as an aspect of the physicochemical and biological properties of 12S toxins (prototoxin and trypsin-activated 12S toxin) and the Ealpha and Ebeta components of each 12S toxin. A molecular weight of 350,000 was determined for each 12S toxin and 150,000 for Ealpha and Ebeta. Owing to the structure comprising the subunits Ealpha and Ebeta, 12S toxins are much more stable than Ealpha at low pH values and high temperatures. Such was also the case with type A 19S toxin and its alpha component. The Ealpha component alone accounts for the total toxicity of type E toxin. The toxic substance detected in the blood of the animals administered 12S toxins orally or parenterally was identified as Ealpha from the molecular size and the chromatographic pattern. Prototoxin escaping from detoxification in the stomach owing to the subunit structure may undergo dissociation in the intestine to release the Ealpha component. After absorption, the activated Ealpha appeared in the circulating blood without any further signs of dissociation or enzymatic digestion. 相似文献
4.
Neurotransmitter-Mediated Regulation of Brain Aromatase: Protein Kinase C- and G-Dependent Induction
Abstract: Aromatase in the diencephalic neurons, the level of which increases transiently during the prenatal to neonatal period, has been suggested to be involved in control of sexual behavior and differentiation of the CNS. Effects of neurotransmitters on levels of aromatase mRNA in cultured neurons were investigated to determine factors regulating the developmental increase that occurs in level of fetal brain aromatase. The expression of aromatase in diencephalic neurons of fetal mice at embryonic day 13, cultured in vitro, was significantly affected by α1 -adrenergic receptor ligands. Aromatase mRNA levels were higher in neurons treated with the α1 -agonist phenylephrine than in control neurons, whereas prazosin, an α1 -antagonist, suppressed this increase, and ligands for α2 - or β-adrenergic receptors did not exert any influence. The profile of α1 -adrenergic receptor subtypes during actual development in vivo suggested that the α1B subtype is in fact responsible for the signal transduction. Substance P, cholecystokinin, neurotensin, and brain natriuretic peptide also increased the level of expression along with phorbol 12-myristate 13-acetate and dibutyryl-cyclic GMP, whereas forskolin and dibutyryl-cyclic AMP caused a decrease. These data indicate that stimulation via α1 (possibly α1B )-adrenergic receptors, as well as receptors of specific neuropeptides, controls the expression of aromatase in embryonic day 13 diencephalic neurons through activation of protein kinase C or G. β-Adrenergic receptors would not appear to participate in the regulation, judging from their developmental profile, although cyclic AMP might be a suppressive second messenger. 相似文献
5.
6.
The Myxococcus xanthus gene, pkn9 , encodes a protein that contains significant homology with eukaryotic Ser/Thr protein kinases. The pkn9 gene was singled out of a previously identified family of kinase genes by amplification techniques that displayed differences in kinase gene expression during selected periods of the M. xanthus life cycle. Pkn9 was constitutively expressed during vegetative growth and upregulated during the aggregation stage of early development. It consists of 589 amino acids, and its N-terminal 394 residues show 38% identity with both Pkn1 and Pkn2 of M. xanthus . This region also shows 29, 25 and 29% identity with myosin light-chain kinase, protein kinase C, and cAMP-dependent protein kinase, respectively. A 22-residue hydrophobic transmembrane domain separates the kinase domain from the 173-residue C-terminal domain that resides on the outside of the inner membrane. The C-terminal domain contains two sets of tandem repeats of 13 and 10 residues which have no known function. When expressed in Escherichia coli under the T7 promoter, Pkn9 was found to be phosphorylated on serine and threonine residues. Disruption of the pkn9 kinase catalytic subdomains I–III by the insertion of a kanamycin-resistance gene resulted in slightly delayed, smaller and more-crowded fruiting bodies, while spore formation was normal. Total deletion of the pkn9 gene caused severely reduced progression through development resulting in light loose mounds that become slightly more compact over time. Development progressed further at the centre than at the edge of the spot, and spore formation was significantly reduced. Two-dimensional gel analysis revealed that both the disruption and the deletion of pkn9 prevented the expression of five membrane proteins (KREP9-1-4). These results suggest that the loss of Pkn9 kinase activity caused altered fruiting-body formation, the absence of the KREP9 proteins in the membrane, and reduced spore production. 相似文献
7.
Conservation of fine-scale DNA marker order in the genomes of rice and the Triticeae. 总被引:6,自引:0,他引:6
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R P Dunford N Kurata D A Laurie T A Money Y Minobe G Moore 《Nucleic acids research》1995,23(14):2724-2728
DNA markers distribute over large chromosomal regions exhibit conservation of order (collinearity) in different cereal species, but it is not known whether this is maintained on a finer scale, i.e. < or = 2 cM. To address this, sets of two or more genetically linked DNA markers were localised to yeast artificial chromosomes containing rice DNA inserts. Linkage analysis of these DNA markers in barley revealed complete correspondence with their genetic order in rice, the distance between linked sequences on rice chromosomes being < 1.6 cM or < or = 1 + 10(6) bp (1 Mb). Thus, DNA markers separated in this range are collinear in rice, barley and, by inference, other members of the Triticeae. These results are discussed with respect to the use of rice as a key system for the isolation of cereal genes. 相似文献
8.
Chara cells without tonoplasts, prepared by replacing the cellsap with EGTA-containing media, showed essentially the samepattern of light-induced changes in membrane potential and membraneresistance as normal cells although the concentrations of ionsand ATP in the cytoplasm decreased considerably (1/31/10)after loss of the tonoplast. Removal of the tonoplast reducedthe rate of photosynthetic O2 evolution to about 50% of thatof normal cells but did not affect the magnitude of light-inducedpotential change. Not a full but a certain level of electronflow seems necessary to activate the putative electrogenic H+-pump.
1 Present address: Department of Botany, Faculty of Science,University of Tokyo, Japan.
2 Present address: Niigata College of Pharmacy, Niigata 950-21,Japan. (Received September 4, 1978; ) 相似文献
9.
Sumiko Narise 《Biochemical genetics》1979,17(5-6):433-444
Two allozymes (MDHf and MDHs) of cytoplasmic malate dehydrogenase of Drosophila virilis were partially purified and their biochemical properties were compared. MDHf has a pH optimum of 9.75 and MDHs one of 9.25 for malate oxidation. Optimal pH for oxaloacetate reduction is 6.75 and 8.0 for MDHf and MDHs, respectively. The Km value for oxaloacetate of MDHs is approximately twice as that of MDHf. No differences were found with respect to thermostability and Km's for malate, NAD+, or NADH. These results are discussed in terms of the physiological role of cytoplasmic malate dehydrogenase of D. virilis.This work was supported in part by grants from the Ministry of Education, Japan, Nos. 134050 and 154205. 相似文献
10.
Kezhong Zhang Sumiko Kurachi Kotoku Kurachi 《The Journal of biological chemistry》2002,277(6):4532-4540
Blood coagulation activity in humans increases with age. We previously identified two genetic elements, age-related stability element (ASE; GAGGAAG) and age-related increase element (AIE; unique stretch of dinucleotide repeats), which were responsible for age-related stable and increasing expression patterns, respectively, and together recapitulated normal age regulation of the human factor IX (hFIX) gene. Here we report the age-regulatory mechanisms of human anticoagulant protein C (hPC), which shows an age-stable pattern of circulatory levels. The murine protein C gene showed an age-related stable expression pattern in general agreement with that of the hPC. Through longitudinal analyses of transgenic mice carrying hPC minigenes, the hPC gene was found to have a functional age-related stability element (hPC ASE; CAGGAAG) in the 5'-upstream proximal region but was found to lack any age-related increase element. Three other ASE-like sequences present in the hPC gene, GAGGAAA and (G/C)AGGATG, also bound nuclear proteins but were not active in the age regulation of the hPC gene. Functional hPC ASE and hFIX ASE were apparently generated through convergent evolution, and hFIX ASE can fully substitute for the hPC ASE in conferring age-related stable expression pattern of the hPC gene. In the presence of the hPC ASE, hFIX AIE can convert the age-stable expression pattern of the hPC gene to a hFIX-like age-related increase pattern. These results support the universality of ASE and AIE functions across different genes. Clearance of hPC protein from the circulation was not significantly affected by age. We now have established the basic mechanisms responsible for the age-related increase of blood coagulation activity. 相似文献