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51.
52.
Photosensitive Chenopodium chlorophyll protein was purifiedby warming the complex in a boiling water bath, followed bypassing it through a Sephadex column. The shape and positionof the absorption band in the absorption spectrum of purifiedchlorophyll protein (HCP668) were the same as those of non-treatedchlorophyll protein (CP668), except for a change in the proteinband in the UV region. The chlorophyll protein retained a quarterof its original photoconvertibility after heat treatment for25 min at 100°C. Results suggested that the chlorophyll-aminoacid residue binding is very stable against heat, and that chlorophyllis protected from decomposition through the rigid binding. The photoconvertibility of HCP668, as well as CP668, dependedstrongly upon pH, with a pronounced decrease below pH 4 andabove pH 6. Optimal convertibility was at pH 5. Above pH 12,convertibility vanished completely. However, pH-inhibited convertibilityof HCP668 was recovered to its original level by returning thepH to neutral. Illuminalion of CP668 in D2O with red light caused a markedincrease in light scattering. This reveals the occurrence ofa conformational change of apoprotein, leading to aggregation. HCP668 was degraded by mechanical treatment to give a smallersized photosensitive chlorophyll protein without loss of photoconvertibility.This small chlorophyll protein did not precipitate in a saturated(NH4)2SO4 solution. The spectral properties of this complexwere identical to those of HCP668 and CP668. (Received March 21, 1972; ) 相似文献
53.
Shohei?Yamaoka Mizuki?Takenaka Tsutomu?Hanajiri Yuu?Shimizu-Ueda Hiroyuki?Nishida Katsuyuki?T.?Yamato Hideya?Fukuzawa Kanji?OhyamaEmail author 《Sexual plant reproduction》2004,16(5):253-257
In lower land plants, genes controlling the transition from vegetative growth to sexual reproduction have not yet been identified. In the dioecious liverwort Marchantia polymorpha, the transition to sexual reproduction accompanied by the formation of sexual organs on the gametophytic thallus is initiated under long-day conditions. By particle bombardment-mediated mutagenesis, we generated a mutant of M. polymorpha that constitutively forms sexual organs. This mutant is fully fertile, showing that the mutation does not affect formation of male or female sexual organs per se. Genetic analysis reveals that this phenotype is caused by mutation of a single autosomal locus, suggesting that this mutation defines or controls a gene regulating the transition to sexual reproduction in M. polymorpha. 相似文献
54.
Tatsumi R Seio K Fujio M Katayama J Horikawa T Hashimoto K Tanaka H 《Bioorganic & medicinal chemistry letters》2004,14(14):3781-3784
A series of 3-substituted 1-azabicyclo[2.2.2]octanes was discovered as the alpha7 nicotinic acetylcholine (alpha7) receptor agonists. It was found that (+)-3-[2-(benzo[b]thiophen-2-yl)-2-oxoethyl]-1-azabicyclo[2.2.2]octane (+)-15b has potent agonistic activity for the alpha7 receptor. 相似文献
55.
The isolation and characterization of methicillin-resistant Staphylococcus aures (MRSA) strains from the bilateral nares of nurses and their gowns are described. MRSA strains could be isolated from eigth of fifty bilateral nares of nurses and two of their gowns. Ten MRSA strains were typed using coagulase typing, and divided into two types, coagulase II and III. In this study, we found a new group (producing toxic shock syndrome toxin -1, coagulase III and staphylococcal enterotoxin C) in Japanese MRSA. Furthermore, we confirmed that MRSA strains originating from bilateral nares of three nurses were identical and two strains isolated from the left naris of one nurse and her gown were also identical by pulsed-field gel electrophoresis. 相似文献
56.
The polypurine/polypyrimidine (PuPy) tracts present in the human genome are known to be scattered among and within chromosomes. In PuPy tract sequences, triplex formation occurs readily under physiological conditions, leaving single-stranded DNAs capable of hybridization with complementary single-stranded DNAs and RNAs. The formation of single-strands and transmolecular triplexes is thought to enable sequences spaced distantly along the genome to associate with each other and organize nuclear DNA into ordered configurations. Triplex-forming DNAs in the human interphase nucleus were analyzed by combining fluorescence in situ "nondenaturing" hybridization employing PuPy tract probes and immunodetection by antitriplex antibodies. The nondenaturing hybridization technique, which has been used to detect RNA, may detect single-stranded DNAs in nondenatured nuclei, if present. Probes such as (GA/TC)(n) and (GAA/TTC)(n) sequences gave sequence-specific signals that overlapped with or were closely associated with triplexes immunolocalized by using known antitriplex antibodies. Pretreatment of nuclei with antitriplex antibodies blocked probe signal formation. Signal formation was resistant to pretreatment of nuclei with RNases but sensitive to single strand-specific nucleases. Triplexes visualized differentially with distinct PuPy tract probes were associated spatially with centromeric sequences in the interphase nucleus in a sequence-specific manner. 相似文献
57.
Downstream E-box-mediated regulation of the human telomerase reverse transcriptase (hTERT) gene transcription: evidence for an endogenous mechanism of transcriptional repression 总被引:26,自引:0,他引:26 下载免费PDF全文
Horikawa I Cable PL Mazur SJ Appella E Afshari CA Barrett JC 《Molecular biology of the cell》2002,13(8):2585-2597
58.
Mizuki Watanabe Takaaki Kobayashi Yoshihiko Ito Hayato Fukuda Shizuo Yamada Mitsuhiro Arisawa Satoshi Shuto 《Bioorganic & medicinal chemistry letters》2018,28(23-24):3630-3633
We previously designed and synthesized a series of histamine analogues with an imidazolylcyclopropane scaffold and identified potent non-selective antagonists for histamine H3 and H4 receptor subtypes. In this study, to develop H4 selective ligands, we newly designed and synthesized cyclopropane-based derivatives having an indole, benzimidazole, or piperazine structure, which are components of representative H4 selective antagonists such as JNJ7777120 and JNJ10191584. Among the synthesized derivatives, imidazolylcyclopropanes 12 and 13 conjugated with a benzimidazole showed binding affinity to the H3 and H4 receptors comparable to that of a well-known non-selective H3/H4 antagonist, thioperamide. These results suggest that the binding modes of the cyclopropane-based H3/H4 ligands in the H4 receptor can be different from those of the indole/benzimidazole-piperazine derivatives. 相似文献
59.
Yoko Akazawa-Ogawa Mizuki Takashima Young-Ho Lee Takahisa Ikegami Yuji Goto Koichi Uegaki Yoshihisa Hagihara 《The Journal of biological chemistry》2014,289(22):15666-15679
The variable domain of camelid heavy chain antibody (VHH) is highly heat-resistant and is therefore ideal for many applications. Although understanding the process of heat-induced irreversible denaturation is essential to improve the efficacy of VHH, its inactivation mechanism remains unclear. Here, we showed that chemical modifications predominantly governed the irreversible denaturation of VHH at high temperatures. After heat treatment, the activity of VHH was dependent only on the incubation time at 90 °C and was insensitive to the number of heating (90 °C)-cooling (20 °C) cycles, indicating a negligible role for folding/unfolding intermediates on permanent denaturation. The residual activity was independent of concentration; therefore, VHH lost its activity in a unimolecular manner, not by aggregation. A VHH mutant lacking Asn, which is susceptible to chemical modifications, had significantly higher heat resistance than did the wild-type protein, indicating the importance of chemical modifications to VHH denaturation. 相似文献
60.
Tsuboi S Sutoh M Hatakeyama S Hiraoka N Habuchi T Horikawa Y Hashimoto Y Yoneyama T Mori K Koie T Nakamura T Saitoh H Yamaya K Funyu T Fukuda M Ohyama C 《The EMBO journal》2011,30(15):3173-3185
The O-glycan branching enzyme, core2 β-1,6-N-acetylglucosaminyltransferase (C2GnT), forms O-glycans containing an N-acetylglucosamine branch connected to N-acetylgalactosamine (core2 O-glycans) on cell-surface glycoproteins. Here, we report that upregulation of C2GnT is closely correlated with progression of bladder tumours and that C2GnT-expressing bladder tumours use a novel strategy to increase their metastatic potential. Our results showed that C2GnT-expressing bladder tumour cells are highly metastatic due to their high ability to evade NK cell immunity and revealed the molecular mechanism of the immune evasion by C2GnT expression. Engagement of an NK-activating receptor, NKG2D, by its tumour-associated ligand, Major histocompatibility complex class I-related chain A (MICA), is critical to tumour rejection by NK cells. In C2GnT-expressing bladder tumour cells, poly-N-acetyllactosamine was present on core2 O-glycans on MICA, and galectin-3 bound the NKG2D-binding site of MICA through this poly-N-acetyllactosamine. Galectin-3 reduced the affinity of MICA for NKG2D, thereby severely impairing NK cell activation and silencing the NK cells. This new mode of NK cell silencing promotes immune evasion of C2GnT-expressing bladder tumour cells, resulting in tumour metastasis. 相似文献