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61.
Changes in the contents of phytate (IP6) and other phosphorus(P)-compoundsin germinating seeds of a huskless barley were investigatedin the embryo with scutellum (EM), the starchy endosperm (EN),and the aleurone layer with pericarp-testa (AL). More than 80%of the total P in the AL of 1-day germinated seeds was foundin acid-soluble organic P, most of which was IP6. During germination,the IP6 in AL decreased markedly with no accumulation of lessphosphorylated myo-inositols and Pi and acid-insoluble organicP increased in the EM. The total P in the EN of 1-day germinatedseeds was about one-third that in the AL, the greater part ofwhich was found in the acid-insoluble fraction and decreasedgradually during germination. Only a small amount of IP6 couldbe detected in the EM and EN during the early stage of germination. IP6 in AL of embryoless half-seeds incubated without gibberellicacid (GA3) decreased slightly even after 6 days. Incubationwith 10 ppm GA3 remarkably stimulated the IP6 degradation. Thisstimulation was reduced, with no change in the Pi content, byabout 8090% with 1 mM 6-methylpurine or 10 ppm cycloheximide.The addition of 0.1 M KH2PO4 caused a 4-fold increase in thePi content of AL in the presence of GA3. In addition, it suppressedthe GA3-dependent -amylase synthesis by about 20% and the GA3effect on IP6 degradation by about 50%. In light of these results, IP6 seems to be hydrolyzed completelyinto Pi and myo-inositol within the aleurone tissue, and gibberellinseems to control this process. (Received August 24, 1979; ) 相似文献
62.
Inactivation of D-glucosyltransferases from oral Streptococcus mutans and Streptococcus sanguis by photochemical oxidation 总被引:2,自引:0,他引:2
Cell-free D-glucosyltransferase of D-glucose-grown Streptococcus mutans AHT was completely inactivated in the presence of 0.002% of Methylene Blue at 25 degrees and pH 7.0 after illumination with a 150-W incandescent lamp. The rate of inactivation was decreased at pH values less than 7.0. Histidine was the only amino acid residue modified to a significant extent, and the rates of oxidation of histidine residues and loss of enzyme activity closely agreed. Production of both water-insoluble and -soluble D-glucan fractions from sucrose by the oxidized D-glucosyltransferase preparations was significantly inhibited. Photooxidation with 0.002% of Rose Bengal at pH 7.0 or higher also induced complete inactivation of the D-glucosyltransferase. These results strongly suggest that the imidazole portion of histidine may function as part of the active sites of both D-glucosyltransferase isozymes of S. mutans AHT, which are responsible for the synthesis of (1 goes to 3)- and (1 goes to 6)-alpha-D-glucosidic linkages. The D-glucosyltransferases from S. mutans 6715 and AHT-mutant M1, and Streptococcus sanguis ATCC 10558 were also almost completely inactivated by Methylene Blue-sensitized photooxidation. 相似文献
63.
Y Kawai H Takahashi T Fujita S Koga 《Biochemical and biophysical research communications》1979,88(2):410-414
The process of bacteriophage T4 morphogenesis was studied using a heat leakage scanning calorimeter. Thermograms of defective mutant 49 (am NG727) in permissive and non-permissive cells of showed a difference in thermal properties between packaged and non-packaged DNA molecules. , non-packaged DNA carried out their thermal transition at 85°C, the same temperature as that of T4 DNA melting measured in the standard saline citrate buffer, while the packaged DNA gave a sharper peak at 87°C due to some interaction with the head shell structure. Empty head shells showed a sharp heat absorption peak at 89°C both and , indicating the high degree of cooperativity in their conformational changes. 相似文献
64.
Hiroyuki Koga Haruka Fujitani Yoshiaki Morino Norio Miyamoto Jun Tsuchimoto Tomoko F. Shibata Masafumi Nozawa Shuji Shigenobu Atsushi Ogura Kazunori Tachibana Masato Kiyomoto Shonan Amemiya Hiroshi Wada 《PloS one》2016,11(2)
Over the course of evolution, the acquisition of novel structures has ultimately led to wide variation in morphology among extant multicellular organisms. Thus, the origins of genetic systems for new morphological structures are a subject of great interest in evolutionary biology. The larval skeleton is a novel structure acquired in some echinoderm lineages via the activation of the adult skeletogenic machinery. Previously, VEGF signaling was suggested to have played an important role in the acquisition of the larval skeleton. In the present study, we compared expression patterns of Alx genes among echinoderm classes to further explore the factors involved in the acquisition of a larval skeleton. We found that the alx1 gene, originally described as crucial for sea urchin skeletogenesis, may have also played an essential role in the evolution of the larval skeleton. Unlike those echinoderms that have a larval skeleton, we found that alx1 of starfish was barely expressed in early larvae that have no skeleton. When alx1 overexpression was induced via injection of alx1 mRNA into starfish eggs, the expression patterns of certain genes, including those possibly involved in skeletogenesis, were altered. This suggested that a portion of the skeletogenic program was induced solely by alx1. However, we observed no obvious external phenotype or skeleton. We concluded that alx1 was necessary but not sufficient for the acquisition of the larval skeleton, which, in fact, requires several genetic events. Based on these results, we discuss how the larval expression of alx1 contributed to the acquisition of the larval skeleton in the putative ancestral lineage of echinoderms. 相似文献
65.
The activation process of pepsinogen was analyzed by a combination of computer simulation and experiment. In order to investigate in detail the behavior of the basic schemes proposed in the previous study, further computer simulations were conducted. Some experiments were performed based on the information obtained. The changes in the UV difference spectrum in the early stage was measured by the stopped-flow technique and the conversion of pepsinogen to pepsin [EC 3.4.23.1] was followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Furthermore, on the basis of the experimental results, the most reasonable scheme was selected and modified. As a result, a scheme for the activation process of pepsinogen was obtained (Scheme 8). On the basis of the above analyses, it was assumed that the first step and the third step are pH-dependent based on the change in the UV spectrum, that the second step is a nonlinear reaction containing a looped reaction with a dimeric intermediate (in this step, peptide fragments are released and pepsinogen is converted to a pepsin-like molecule), and that the third step is an equilibrium reaction involving proton binding. 相似文献
66.
Extracellular d-glucosyltransferases (GTase) and d-fructosyltransferases (FTase) were isolated from Streptococcus mutans IB (serotype c), B14 (e), and OMZ175 (f) by chromatofocusing, followed by hydroxyapatite column chromatography. The GTases isolated from serotypes c, e, and f are basic proteins (pI 7.4). The serotype c and e enzymes have two protein components having Mr 173 000 and 158 000 and the enzyme of the serotype f one component having Mr 156 000. The GTases of all the serotypes showed a Km value for sucrose of 10–14mm and an optimum pH 5.5–6.0 for enzyme activity, and their activities were enhanced by the presence of primer Dextran T10. The α-d-glucans synthesized by the purified GTases are water soluble and primarily consist of (1→6)-α-d-glucosidic linkage (41–66 mol/100 mol) and α-d-(1→3,6)-branch linkage (6–20 mol/100 mol), but significant proportions of α-d-(1→3), α-d-(1→4), and α-d-(1→3,4) linkages (11, 6, and 14 mol/100 mol, respectively) were detected in the serotype c α-d-glucan. The isolated FTases of the serotypes c, e, and f are acidic enzymes (pI 4.6) and consist of two components having Mr 84 000 and 76 000 for the serotype c enzyme, and 106 000 and 84 000 for the serotypes e and f enzymes, respectively. The Km value for sucrose was 6, 10, and 17mm for the serotypes c, e, and f enzymes, respectively, and the optimum pH of enzymic activity 5.5–6.0. Reactivity with Concanavalin A, susceptibility to acid hydrolysis, and paper chromatography of the hydrolyzates suggested that the water-soluble β-d-fructans synthesized by the purified FTases were of the inulin-type and had chemical structures somewhat different among the serotypes. 相似文献
67.
Yorishige Imamura Toshihisa Koga Hideaki Shimada Masaki Otagiri 《Journal of enzyme inhibition and medicinal chemistry》2013,28(1):35-39
The chemical modifications of rabbit liver carbonyl reductase (RLCR) with phenylglyoxal (PGO) and 2,3,4-trinitrobenzenesulfonate sodium (TNBS), which are respective chemical modifiers of arginine and lysine residues, were examined. RLCR was rapidly inactivated by these modifiers. Kinetic data for the inactivation demonstrated that each one of arginine and lysine residues is essential for catalytic activity of the enzyme. Furthermore, based on the protective effects of NADP +, NAD + and their constituents against the inactivation of RLCR by PGO and TNBS, we propose the possibility that the functional arginine and lysine residues are located in the coenzyme-binding domain of RLCR and interact with the 2′-phosphate group of NADPH. 相似文献
68.
Ornjira Prakhongcheep Yuriko Hirai Toru Hara Kornsorn Srikulnath Hirohisa Hirai Akihiko Koga 《DNA research》2013,20(3):235-240
Alpha satellite DNA is a repetitive sequence known to be a major DNA component of centromeres in primates (order Primates). New World monkeys form one major taxon (parvorder Platyrrhini) of primates, and their alpha satellite DNA is known to comprise repeat units of around 340 bp. In one species (Azara''s owl monkey Aotus azarae) of this taxon, we identified two types of alpha satellite DNA consisting of 185- and 344-bp repeat units that we designated as OwlAlp1 and OwlAlp2, respectively. OwlAlp2 exhibits similarity throughout its entire sequence to the alpha satellite DNA of other New World monkeys. The chromosomal locations of the two types of sequence are markedly distinct: OwlAlp1 was observed at the centromeric constrictions, whereas OwlAlp2 was found in the pericentric regions. From these results, we inferred that OwlAlp1 was derived from OwlAlp2 and rapidly replaced OwlAlp2 as the principal alpha satellite DNA on a short time scale at the speciation level. A less likely alternative explanation is also discussed. 相似文献
69.
70.
Giannina Descalzi Tao Chen Kohei Koga Xiang‐Yao Li Kaori Yamada Min Zhuo 《Journal of neurochemistry》2013,126(5):636-650
Recent investigations into the mechanisms mediating itch transmission have focused on spinal mechanisms, whereas few studies have investigated the role of the cerebral cortex in itch‐related behaviors. Human imaging studies show that several cortical regions are active in correspondence with itch, including the anterior cingulate cortex (ACC). We present here evidence of cortical modulation of pruritogen‐induced scratching behavior. We combine pharmacological, genetic, and electrophysiological approaches to show that cortical GluK1‐containing kainate (KA) receptors are involved in scratching induced by histamine and non‐histamine‐dependent itching stimuli. We further show that scratching corresponds with enhanced excitatory transmission in the ACC through KA receptor modulation of inhibitory circuitry. In addition, we found that inhibiting GluK1‐containing KA receptors in the ACC also reduced behavioral nociceptive responses induced by formalin. Our results reveal a new role of the cortex in pruritogen‐induced scratching.