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531.
532.
Kenji Kangawa Naoto Minamino Naoyoshi Chino Shumpei Sakakibara Hisayuki Matsuo 《Biochemical and biophysical research communications》1981,99(3):871-878
After re-purification by reverse phase high performance liquid chromatography, α-neo-endorphin was submitted to structural analyses, performed by dansyl-Edman degradation, as well as by C-terminal analysis by 3H-labeling. The full sequence of α-neo-endorphin has been determined to be : Tyr-Gly-Gly-Phe-Leu-Arg-Lys-Tyr-Pro-Lys, in which the 8th residue previously reported as Arg is found to be Tyr. A synthetic decapeptide with the above sequence was verified to be identical with natural α-neo-endorphin. For further structural confirmation, tryptic and chymotryptic peptides were also identified. Thus, the complete sequence of α-neo-endorphin has been definitely established. Its potent opioid activity in the guinea-pig ileum assay is also discussed. 相似文献
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535.
H Kuroda S Kubo N Chino T Kimura S Sakakibara 《International journal of peptide and protein research》1992,40(2):114-118
When L-proline or O-benzyl-trans-4-hydroxy-L-proline phenacyl ester was coupled with Boc-amino acids in dimethylformamide using water-soluble carbodiimide (WSCI) in the presence of anhydrous 1-hydroxybenzotriazole (HOBt) as coupling reagents, extensive racemization was observed at the C alpha of the proline or hydroxy-proline residue. The extent of racemization was measured by HPLC after the coupling with Boc-L-Leu-OH in the presence or absence of HOBt. The extent of racemization increased when HOBt was added to the reaction mixture, but greatly decreased when it was not, indicating that HOBt was needed for inducing racemization. Almost no racemization was observed when the coupling reaction was carried out by the mixed anhydride procedure in tetrahydrofuran or by the carbodiimide method in dichloromethane without using HOBt. In the case of coupling reactions with ordinary L-amino acid phenacyl esters, no racemization was observed. Examination of some model systems yielded sufficient evidence to prove that HOBt is an efficient catalyst for racemizing proline or hydroxy-proline phenacyl ester not only in the stage of cyclic intermediate formation but also in the opening of the ring structure. Thus, the racemization reaction was found to be closely related to the formation of the cyclic carbinol-amine derivative. 相似文献
536.
Arai Haruka Yanagiura Kazuya Toyama Yuko Morohashi Kengo 《Journal of plant research》2019,132(2):197-209
Journal of Plant Research - The evolution of plants on land required adaptation to UV radiation and dry environments, and involved the appearance and/or rewiring of genetic connections, known as... 相似文献
537.
Calcium ion is a secondary messenger that mediates a variety of physiological responses of neurons, including cell survival
responses. To determine the role of calcium in regulating neuronal survival and death, we examined whether chelation of extracellular
calcium with EGTA induces caspase-dependent apoptotic cell death and whether glycogen synthase kinase-3 is involved in EGTA-induced
cell death in PC12 cells. EGTA increased apoptotic cell death with morphological changes characterized by cell shrinkage and
nuclear condensation and fragmentation accompanied by caspase activation. EGTA increased GRP78 protein expression, suggesting
that EGTA induces ER stress. Glycogen synthase kinase-3 inhibitors prevented EGTA-induced apoptosis. In addition, nerve growth
factor and insulin growth factor-I completely blocked EGTA-induced cell death. Moreover, caspase-3 activation was inhibited
by glycogen synthase kinase-3 inhibitors. These results suggest that chelation of extracellular calcium with EGTA induces
caspase-dependent apoptosis, and the activation of glycogen synthase kinase-3 is involved in the death of PC12 cells. 相似文献
538.
Phosphatidic acid (PA) is the simplest phospholipid and is involved in the regulation of various cellular events. Recently, we developed a new PA sensor, the N-terminal region of α-synuclein (α-Syn-N). However, whether α-Syn-N can sense physiologically produced, endogenous PA remains unclear. We first established an inactive PA sensor (α-Syn-N-KQ) as a negative control by replacing all eleven lysine residues with glutamine residues. Using confocal microscopy, we next verified that α-Syn-N, but not α-Syn-N-KQ, detected PA in macrophagic phagosomes in which PA is known to be enriched, further indicating that α-Syn-N can be used as a reliable PA sensor in cells. Finally, because PA generated during neuronal differentiation is critical for neurite outgrowth, we investigated the subcellular distribution of PA using α-Syn-N. We found that α-Syn-N, but not α-Syn-N-KQ, accumulated at the peripheral regions (close to the plasma membrane) of neuronal growth cones. Experiments using a phospholipase D (PLD) inhibitor strongly suggested that PA in the peripheral regions of the growth cone was primarily produced by PLD. Our findings provide a reliable sensor of endogenous PA and novel insights into the distribution of PA during neuronal differentiation. 相似文献
539.
Haruka Yoshimura Hui Zhu Yunying Wu Ruijun Ma 《International journal of biometeorology》2010,54(2):179-191
Human exposure to harmful ultraviolet (UV) radiation has important public health implications. Actual human exposure to solar
UV radiation depends on ambient UV irradiance, and the latter is influenced by ground reflection. In urban areas with higher
reflectivity, UV exposure occurs routinely. To discover the solar UV radiation regulation mechanism of vegetation, the spectral
reflectance and transmittance of plant leaves were measured with a spectrophotometer. Typically, higher plants have low leaf
reflectance (around 5%) and essentially zero transmittance throughout the UV region regardless of plant species and seasonal
change. Accordingly, incident UV radiation decreases to 5% by being reflected and is reduced to zero by passing through a
leaf. Therefore, stratified structures of vegetation are working as another terminator of UV rays, protecting whole terrestrial
ecosystems, while vegetation at waterfronts contributes to protect aquatic ecosystems. It is possible to protect the human
population from harmful UV radiation by urban landscape design of tree shade and the botanical environment. Even thin but
uniformly distributed canopy is effective in attenuating UV radiation. To intercept diffuse radiation, UV screening by vertical
structures such as hedges should be considered. Reflectivity of vegetation is around 2%, as foliage surfaces reduce incident
UV radiation via reflection, while also eliminating it by transmittance. Accordingly, vegetation reduces incident UV radiation
to around 2% by reflection. Vegetation influence on ambient UV radiation is broad-spectrum throughout the UV region. Only
trees provide cool UV protective shade. Urban landscapes aimed at abating urban heat islands integrated with a reduction of
human UV over-exposure would contribute to mitigation of climate change. 相似文献