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91.
Matsui T Nakajima A Fujii H Matera KM Migita CT Yoshida T Ikeda-Saito M 《The Journal of biological chemistry》2005,280(44):36833-36840
Heme oxygenase (HO) catalyzes the catabolism of heme to biliverdin, CO, and a free iron through three successive oxygenation steps. The third oxygenation, oxidative degradation of verdoheme to biliverdin, has been the least understood step despite its importance in regulating HO activity. We have examined in detail the degradation of a synthetic verdoheme IXalpha complexed with rat HO-1. Our findings include: 1) HO degrades verdoheme through a dual pathway using either O(2) or H(2)O(2); 2) the verdoheme reactivity with O(2) is the lowest among the three O(2) reactions in the HO catalysis, and the newly found H(2)O(2) pathway is approximately 40-fold faster than the O(2)-dependent verdoheme degradation; 3) both reactions are initiated by the binding of O(2) or H(2)O(2) to allow the first direct observation of degradation intermediates of verdoheme; and 4) Asp(140) in HO-1 is critical for the verdoheme degradation regardless of the oxygen source. On the basis of these findings, we propose that the HO enzyme activates O(2) and H(2)O(2) on the verdoheme iron with the aid of a nearby water molecule linked with Asp(140). These mechanisms are similar to the well established mechanism of the first oxygenation, meso-hydroxylation of heme, and thus, HO can utilize a common architecture to promote the first and third oxygenation steps of the heme catabolism. In addition, our results infer the possible involvement of the H(2)O(2)-dependent verdoheme degradation in vivo, and potential roles of the dual pathway reaction of HO against oxidative stress are proposed. 相似文献
92.
Gibberellins A1/3 (GA1/3) and GA20 appeared earlier in surrounding tissues (pericarps/carpel/placenta) than in developing seeds of morning glory. The content of GA1/3 became higher in seeds than in the surrounding tissues at 9 days after anthesis (DAA), while that of GA20 stayed lower in seeds even at 12 DAA, suggesting the possibility that GA20 was translocated into seeds from the surrounding tissues and converted to GA1/3. The site of biosynthesis of GA20 in the fruits was determined by RNA-blotting and in situ hybridization of GA 20-oxidase genes (InGA20ox1, InGA20ox2). InGA20ox1 was not expressed in the surrounding tissues but in seeds, while no signal due to InGA20ox2 was detected in neither tissue. The expression of InGA20ox1 started in the seed coat near the hilum and spread in the seed coat like those of GA 3-oxidase and GA-inducible alpha-amylase genes. These observations suggest that GA biosynthesis is tissue-specifically and time-dependently regulated in the fruit of morning glory. 相似文献
93.
In this study, human α-1,4-N-acetylglucosaminyltransferase (α4GnT) fused with GFPuv (GFPuv-α4GnT) was expressed using both a transformed cell system and silkworm larvae. A Tn-pXgp-GFPuv-α4GnT cell line, isolated after expression vector transfection, produced 106 mU/ml of α4GnT activity in suspension culture.
When Bombyx mori nucleopolyhedrovirus containing a GFPuv-α4GnT fusion gene (BmNPV-CP
−/GFPuv-α4GnT) bacmid was injected into silkworm larvae, α4GnT activity in larval hemolymph was 352 mU/ml, which was 3.3-fold higher
than that of the Tn-pXgp-GFPuv-α4GnT cell line. With human calnexin (CNX) or human immunoglobulin heavy chain-binding protein (BiP, GRP78) coexpressed under
the control of the ie-2 promoter, α4GnT activity in larval hemolymph increased by 1.4–2.0-fold. Moreover, when BmNPV-CP
−/GFPuv-α4GnT bacmid injection was delayed for 3 h after BmNPV-CP
−/CNX injection, the α4GnT activity increased significantly to 922 mU/ml, which was 8.7-fold higher than that of the Tn-pXgp-GFPuv-α4GnT cell line. Molecular chaperone assisted-expression in silkworm larvae using the BmNPV bacmid is a promising tool for
recombinant protein production. This system could lead to large-scale production of more complex recombinant proteins. 相似文献
94.
95.
Human insulin gene is a target gene of hepatocyte nuclear factor-1alpha (HNF-1alpha) and HNF-1beta. 总被引:6,自引:0,他引:6
96.
Ishihara K Yamamoto H Mitsuhashi K Nishikawa K Tsuboi S Tsuji H Nakajima N 《Bioscience, biotechnology, and biochemistry》2004,68(11):2306-2312
An NADPH-dependent alpha-keto amide reductase was purified from Saccharomyces cerevisiae. The molecular mass of the native enzyme was estimated to be 33 and 36 kDa by gel filtration chromatography and SDS-polyacrylamide gel electrophoresis, respectively. The purified enzyme showed a reducing activity not only for aromatic alpha-keto amides but also for aliphatic and aromatic alpha-keto esters. The internal sequence of the enzyme was identical with that of a hypothetical protein (ORF YDL 124w) coded by yeast chromosome IV. 相似文献
97.
The “paradox of enrichment” predicts that increasing the growth rate of the resource in a resource-consumer dynamic system,
by nutrient enrichment, for example, can lead to local instability of the system—that is, to a Hopf bifurcation. The approach
to the Hopf bifurcation is accompanied by a decrease in resilience (rate of return to equilibrium). On the other hand, studies
of nutrient cycling in food webs indicate that an increase in the nutrient input rate usually results in increased resilience.
Here these two apparently conflicting theoretical results are reconciled with a model of a nutrient-limited resource-consumer
system in which the tightly recycled limiting nutrient is explicitly modelled. It is shown that increasing nutrient input
may at first lead to increased resilience and that resilience decreases sharply only immediately before the Hopf bifurcation
is reached. 相似文献
98.
Takaishi K Alen Y Kawazu K Baba N Nakajima S 《Bioscience, biotechnology, and biochemistry》2004,68(11):2398-2400
Several 3-alkylphenols including 3-undecylphenol, which was isolated from a Sumatran rainforest plant, were synthesized to investigate their antinematodal activity against the phytopathogenic nematodes, Bursapherencus xylophilus. A three-step synthesis involving the treatment of 2-cyclohexen-1-one with the Grignard reagent, oxidation of the resulting 1-alkyl-2-cyclohexen-1-ol and subsequent aromatization of 3-alkyl-2-cyclohexen-1-one successfully afforded such phenols. Among the 3-alkylphenols, 3-nonylphenol showed the highest activity, while 3-decylphenol and 3-undecylphenol also showed high activity. 相似文献
99.
Y. Otsu Y. Matsuda H. Mori H. Ueki T. Nakajima K. Fujiwara M. Matsumoto N. Azuma K. Kakutani T. Nonomura Y. Sakuratani T. Shinogi Y. Tosa S. Mayama H. Toyoda 《Biocontrol Science and Technology》2004,14(5):427-439
An entomopathogenic bacterium was isolated from tomato leaves and used as a microbial agent to control larvae of phytophagous ladybird beetles Epilachna vigintioctopunctata. The isolate was identified as Pseudomonas fluorescens KPM-018P on the basis of its bacteriological characteristics. KPM-018P produced extracellular chitinase to form a transparent zone around their colonies by hydrolyzing chitin in a minimal medium. Pale-yellow colonies turned red after a change of incubation temperature. These characteristics were availed as markers for tracking KPM-018P. The bacteria produced biosurfactants that enabled the bacteria to stably colonize the hydrophobic leaf surface; they were recovered without any considerable decrease even after a suspension of KPM-018P was sprayed onto leaves. KPM-018P, transformed with the gfp gene and observed with fluorescence microscopy, stably dwelled in the junctions of epidermal cells of bacteria-sprayed leaves. Ingestion of KPM-018P-sprayed leaves by the larvae caused prompt death of these insects to eventually suppress their pupation. This method is thus effective for decreasing the population of larvae and adult insect pests in the subsequent generation. The study provides an experimental basis for the biocontrol of herbivorous insect pests using a leaf-inhabiting, entomopathogenic strain of P. fluorescens. 相似文献
100.
Cloning of human muscle phosphofructokinase cDNA 总被引:7,自引:0,他引:7
Three overlapping cDNA clones for human muscle phosphofructokinase (HMPFK) covering the complete coding sequence were isolated. The sequence included a poly(A) tail, a 399 bp 3'-untranslated region, a 2337 bp coding region for 779 amino acid residues and a part of the 5'-untranslated region. Homologies between HMPFK and rabbit muscle phosphofructokinase (RMPFK) were 96% of the amino acids and 89% of the nucleotides in the coding region. Like RMPFK, HMPFK also possessed the internal homology between C- and N-halves in its primary structure. Cloning of HMPFK cDNA will help to identify the molecular defect in patients with glycogenosis type VII (HMPFK deficiency). 相似文献