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131.
Sequential conversion of molecular oxygen into peroxo- and hydroperoxo-metal species involved in an effective O2-activation is verified for the TpiPr2Rh system by isolation and characterization of the intermediates. O2-treatment of the Rh(I) precursor, TpiPr2Rh(dppe) (1), in the presence of 3,5-diisopropylpyrazole (H-pziPr2) gives the κ2-peroxometal complex, TpiPr2(H-pziPr2)Rh(κ2-O2) (2), which is subsequently converted to the hydroperoxo complex, TpiPr2(H-pzH2)(pzH2)Rh-OOH (4), upon treatment with pyrazole (H-pzH2). The peroxo species 2 and 4 have been characterized by spectroscopic and crystallographic methods and it is revealed that, in the present N-rich coordination system, the basic peroxo ligands (O2, OOH) form hydrogen-bonding interactions with the proximal N- and NH-functional groups. 相似文献
132.
Zhou Z Yamamoto Y Sugai F Yoshida K Kishima Y Sumi H Nakamura H Sakoda S 《The Journal of biological chemistry》2004,279(26):27320-27326
Hepatoma-derived growth factor (HDGF) is a heparin-binding proliferating factor originally isolated from conditioned medium of the hepatoma-derived cell line HuH-7. HDGF has greatest homology in an amino acid sequence with high mobility group 1 (HMG1), which has been characterized as a DNA-binding, inflammatory, and potent neurite outgrowth molecule. HDGF is reported to be widely expressed and act as a growth factor in many kinds of cells. However, it has not been investigated in the nervous system. Here, we show by Western blot analysis that HDGF is present in the mouse brain from the embryonic period until adulthood. In situ hybridization and immunohistochemical analyses revealed that HDGF was expressed mainly in neurons, and HDGF protein was localized to the nucleus. HDGF and high mobility group 1 were secreted under physiological conditions and released extracellularly in necrotic conditions. Furthermore, we showed that exogenously supplied HDGF had a neurotrophic effect and was able to partially prevent the cell death of neurons in which endogenous HDGF was suppressed. Therefore, we propose that HDGF is a novel type of neurotrophic factor, on account of its localization in the nucleus and its potential to function in an autocrine manner under both physiological and pathological conditions throughout life. 相似文献
133.
Tashima Y Oe R Lee S Sugihara G Chambers EJ Takahashi M Yamada T 《The Journal of biological chemistry》2004,279(17):17587-17595
In order to investigate the influence of cholesterol (Ch) and monosialoganglioside (GM1) on the release and subsequent deposition/aggregation of amyloid beta peptide (Abeta)-(1-40) and Abeta-(1-42), we have examined Abeta peptide model membrane interactions by circular dichroism, turbidity measurements, and transmission electron microscopy (TEM). Model liposomes containing Abeta peptide and a lipid mixture composition similar to that found in the cerebral cortex membranes (CCM-lipid) have been prepared. In all, four Abeta-containing liposomes were investigated: CCM-lipid; liposomes with no GM1 (GM1-free lipid); those with no cholesterol (Ch-free lipid); liposomes with neither cholesterol nor GM1 (Ch-GM1-free lipid). In CCM liposomes, Abeta was rapidly released from membranes to form a well defined fibril structure. However, for the GM1-free lipid, Abeta was first released to yield a fibril structure about the membrane surface, then the membrane became disrupted resulting in the formation of small vesicles. In Ch-free lipid, a fibril structure with a phospholipid membrane-like shadow formed, but this differed from the well defined fibril structure seen for CCM-lipid. In Ch-GM1-free lipid, no fibril structure formed, possibly because of membrane solubilization by Abeta. The absence of fibril structure was noted at physiological extracellular pH (7.4) and also at liposomal/endosomal pH (5.5). Our results suggest a possible role for both Ch and GM1 in the membrane release of Abeta from brain lipid bilayers. 相似文献
134.
Narimatsu S Imoto K Isobe T Kiryu K Naito S Hichiya H Funae Y Hanioka N Yamamoto S 《Biochemical and biophysical research communications》2004,324(2):627-633
The effects of the substitution of amino acid residues at positions 43 and 45 of rat CYP2D1 and CYP2D2 on their microsomal contents and enzymatic functions were examined. The substitution of Val-45 of CYP2D1 by glycine decreased the microsomal content, whereas the substitution of Gly-45 of CYP2D2 by valine increased. The substitution of Leu-43 of CYP2D2 by tryptophan also increased the microsomal protein content. In reduced CO-difference spectra, CYP2D2 showed a P420 peak as well as a P450 peak, whereas CYP2D1 gave only a P450 peak. The substitution of Leu-43 and Gly-45 of CYP2D2 by valine and tryptophan, respectively, markedly decreased the P420 peak in parallel with an increase in P450 content. These substitutions did not cause remarkable changes in drug oxidation capacities (bufuralol 1'-hydroxylation and debrisoquine 4-hydroxylation) of the recombinant enzymes in terms of nmol/min/nmol CYP. The results indicate that amino acid residues at positions 43 and 45 are important for anchoring of the rat CYP2D proteins and their stabilities in the endoplasmic reticulum membrane. 相似文献
135.
Mycobacterium tuberculosis-induced CXCR4 and chemokine expression leads to preferential X4 HIV-1 replication in human macrophages 总被引:4,自引:0,他引:4
136.
Maki S Miyauchi T Kakinuma Y Sakai S Kobayashi T Sugiyama F Fukamizu A Goto K Yamaguchi I 《Life sciences》2004,74(9):1105-1118
Endothelin (ET)-1 and ET-2 are potent vasoconstrictor peptides with mitogenic activity. In this study, we investigated roles of ET system in renin-angiotensin system (RAS)-mediated hypertension, using transgenic hypertensive mice (THM) with over-expression of both human renin and angiotensinogen genes. In the first step, it was revealed that expression of ET system was locally enhanced, i.e. increases in cardiac preproET-1 mRNA and renal preproET-2 mRNA in THM, compared with the control (wild type) mice. In the next step, we studied the chronic effects of an ET antagonist (SB209670) on THM. Blood pressure (BP) in THM was significantly higher than that in the normal mice during the investigation. However, in the later phase of the study, from 12 to 20 weeks of treatment, THM receiving SB 209670 showed significantly lower BP than that in THM receiving saline. SB 209670 treatment for 20 weeks significantly attenuated phenotypes of cardiac hypertrophy, vascular wall thickening and hypertensive nephropathy observed in THM, suggesting that the ETA/B receptor antagonist is also effective even in the extraordinarily activated RAS condition. These findings suggest that organ specifically activated ET system in THM develops the phenotypes, hypertension, cardiac hypertrophy, and hypertensive nephropathy. 相似文献
137.
Kominato Y Ueki M Iida R Kawai Y Nakajima T Makita C Itoi M Tajima Y Kishi K Yasuda T 《The FEBS journal》2006,273(13):3094-3105
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