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231.
Takahashi YT Sasaki H Takayama SJ Mikami S Kawano S Mita H Sambongi Y Yamamoto Y 《Biochemistry》2006,45(36):11005-11011
Thermophile Hydrogenobacter thermophilus cytochrome c(552) (HT) is a stable protein with denaturation temperatures (T(m)) of 109.8 and 129.7 degrees C for the oxidized and reduced forms, respectively [Uchiyama, S., Ohshima, A., Nakamura, S., Hasegawa, J., Terui, N., Takayama, S. J., Yamamoto, Y., Sambongi, Y., and Kobayashi, Y. (2004) J. Am. Chem. Soc. 126, 14684-14685]. The removal of a single hydroxyl group from the hydrophobic core of HT, through the replacement of a Tyr by Phe, resulted in further elevation of the T(m) value of the oxidized form by approximately 6 degrees C, the T(m) value of the reduced one remaining essentially unaltered. As a result, the redox potential of the mutant with higher stability in the oxidized form exhibited a negative shift of approximately 20 mV relative to that of wild-type HT in an enthalpic manner. These findings indicated that the redox function of a protein can be enthalpically regulated through the stability of the oxidized form by altering the contextual stereochemical packing of hydrophobic residues in the protein interior using protein engineering. 相似文献
232.
Takayama Y Kobayashi Y Yahata N Saitoh T Hori H Ikegami T Akutsu H 《Biochemistry》2006,45(10):3163-3169
Carbon monoxide (CO) has been identified as another bioactive molecule like NO. Binding of CO to a tetraheme cytochrome c(3) (cyt c(3)) was investigated using visible absorption spectroscopy, circular dichroism (CD), and NMR. CO was found to bind to the four hemes in different manners. CD spectra, however, indicated that only single-site CO binding can keep the protein intact. The K(d) for the single-site binding was 8.0 microM, which is a typical value for a CO sensor protein. Furthermore, NMR spectra of uniformly (15)N-labeled and specifically [(15)N]His-labeled proteins have provided evidence that CO specifically binds to the sixth coordination site of heme 2 via single-site binding. The CO-bound cyt c(3) could conduct redox reactions. In light of triheme cytochrome c(7), the CO-bound cyt c(3) may work as an electron transporter. It was reported for sulfate-reducing bacteria that CO can be used as an energy source and CO cycling is operating like H(2) cycling. Therefore, the CO-bound cyt c(3) may play a role in maintaining electron transport pathways on accumulation of toxic CO for its utilization. 相似文献
233.
To identify the genetic basis of the differences between chimpanzees and humans, it is indispensable to analyze a whole gene set constituting a particular regulatory system as well as to compare the whole genome or chromosomes randomly. We compared genes encoding hormones of the endocrine system, one of the most fundamental regulatory systems in organisms. The present study covered a total of 111 genes generating 115 precursors and 172 peptides. Decisive differences were observed in GNRH2 and UCN2 and their corresponding receptor genes. It is often postulated that mechanisms underlying the basic functions of life are common and would not be readily altered. The present study demonstrated that, on the contrary, substantial differences have been generated in genes composing the endocrine system, even between humans and our closest living relative. 相似文献
234.
Usman H Hakim EH Harlim T Jalaluddin MN Syah YM Achmad SA Takayama H 《Zeitschrift für Naturforschung. C, Journal of biosciences》2006,61(3-4):184-188
A new flavanone, 7-hydroxy-5,6-dimethoxyflavanone (1), together with three other flavonoids, didymocarpin (2), 2',4'-dihydroxy-5',6'-dimethoxychalcone (3), and isodidymocarpin (4), had been isolated from the methanol extract of the tree bark of Cryptocarya costata. The structures of these compounds were determined based on spectral evidence, including UV, IR, 1-D and 2-D NMR, and mass spectra. Cytotoxic properties of compounds 1-4 were evaluated against murine leukemia P-388 cells. The chalcones 3 and 4 were found to have substantial cytotoxicity with IC50 of 5.7 and 11.1 microM, respectively. 相似文献
235.
Differential selectivity of hyaluronidase inhibitors toward acidic and basic hyaluronidases 总被引:1,自引:0,他引:1
Hyaluronidase (HAase), a class of enzymes which degrade hyaluronic acid (HA), are involved in the spread of infections/toxins, ovum fertilization, and cancer progression. Thus, HAase inhibitors may have use in disease treatments. We evaluated 21 HAase inhibitors against HYAL-1, testicular, honeybee, and Streptomyces HAases. Among these inhibitors, polymers of poly (styrene-4-sulfonate) (PSS) (i.e., molecular weight 1400-990,000 or PSS 1400-PSS 990,000) and O-sulfated HA (sHA) derivatives (sHA2.0, 2.5, and 2.75) were the most effective. HYAL-1 and bee HAases were the most sensitive, followed by testicular HAase; Streptomyces HAase was resistant to all inhibitors, except PSS 990,000 and VERSA-TL 502 (i.e., PSS 10(6) dalton). The length of the PSS polymer determined their potency (e.g., IC50 for HYAL-1, PSS 990,000: 0.0096 microM; PSS 210 no inhibition; IC50 for testicular HAase, PSS 990,000: 0.042 microM; PSS 210 no inhibition). The presence, but not the number, of sulfate groups on the sHA molecule determined its potency (e.g., IC50 for HYAL-1: sHA2.0, 0.019 microM; sHA2.75, 0.0083 microM). Other known HAase inhibitors, such as gossypol, sodium-aurothiomalate, 1-tetradecane sulfonic acid, and glycerrhizic acid, were not effective. Both PSS and sHA inhibited HAases by a mixed inhibition mechanism (i.e., competitive + uncompetitive) and were 5- to 17-fold better as uncompetitive inhibitors than as competitive inhibitors. These results demonstrate that HAase inhibitors show selectivity toward the different types of HAases, which could be exploited to inhibit specific HAases involved in a variety of pathophysiologic conditions. 相似文献
236.
Phylogenetic relationships and the spatial genetic structure of a pantropical plant with sea-drifted seeds, Hibiscus tiliaceus L., and its allied species were investigated. The combined distribution range of these species is over almost the entire littoral area of the tropics worldwide, which might result from the dispersal of their sea-drifted seeds and from recurrent speciation in local populations. A phylogenetic tree constructed using the nucleotide sequences of a c. 7500-bp portion of chloroplast DNA suggested the possibility that recurrent speciation from H. tiliaceus has given rise to all of its allied species. Three major sequence haplotypes of H. tiliaceus had wide and overlapping distributions throughout the Pacific, Atlantic and Indian Ocean regions. This distribution pattern was also confirmed by PCR-SSCP (polymerase chain reaction amplification with single-strand conformation polymorphism) and PCR-SSP (PCR amplification with sequence specific primers) analyses performed on more than 1100 samples from 65 populations worldwide. Statistical analysis using F(ST) and analysis of molecular variance did not show significant genetic differentiation among the H. tiliaceus populations in the three oceanic regions. The results reported here suggested substantial gene flow occurred between populations in the different oceanic regions due to sea-drifted seeds. A strong genetic difference between the Pacific and Atlantic populations of Hibiscus pernambucensis Arruda was observed, which indicates that gene flow in this species between the two regions has been prevented. The wide and dominant distribution of a haplotype shared by H. pernambucensis and H. tiliaceus in the Atlantic region suggests significant introgression between the two species in this region. 相似文献
237.
Ryo Nakabayashi Makoto Kobayashi Keiko Yonekura-Sakakibara Mami Yamazaki Mariko Kitajima Hiromitsu Takayama 《Phytochemistry》2009,70(8):1017-1029
In order to conduct metabolomic studies in a model plant for genome research, such as Arabidopsis thaliana (Arabidopsis), it is a prerequisite to obtain structural information for the isolated metabolites from the plant of interest. In this study, we isolated metabolites of Arabidopsis in a relatively non-targeted way, aiming at the construction of metabolite standards and chemotaxonomic comparison. Anthocyanins (5 and 7) called A8 and A10 were isolated and their structures were elucidated as cyanidin 3-O-[2-O-(β-d-xylopyranosyl)-6-O-(4-O-(β-d-glucopyranosyl)-E-p-coumaroyl)-β-d-glucopyranoside]-5-O-[6-O-(malonyl)-β-d-glucopyranoside] and cyanidin 3-O-[2-O-(2-O-(E-sinapoyl)-β-d-xylopyranosyl)-6-O-(4-O-(β-d-glucopyranosyl)-E-p-coumaroyl)-β-d-glucopyranoside]-5-O-[β-d-glucopyranoside] from analyses of 1D NMR, 2D NMR (1H NMR, NOE, 13C NMR, HMBC and HMQC), HRFABMS, FT-ESI-MS and GC-TOF-MS data. In addition, 35 known compounds, including six anthocyanins, eight flavonols, one nucleoside, one indole glucosinolate, four phenylpropanoids and a derivative, together with three indoles, one carotenoid, one apocarotenoid, three galactolipids, two chlorophyll derivatives, one steroid, one hydrocarbon, and two dicarboxylic acids, were also isolated and identified from their spectroscopic data. 相似文献
238.
Kaori Tanaka Tsukasa Hori Naoki Hatakeyama Masaki Yamamoto Rumiko Takayama Yuko Yoto Nobuhiro Suzuki Toshiaki Hayashi Yukiho Ikeda Hiroshi Ikeda Tadao Ishida Hiroyuki Tsutsumi 《Microbiology and immunology》2009,53(6):319-322
BK polyomavirus (BKV) is ubiquitous among humans, usually infecting them asymptomatically during childhood. BKV persists in renal tissue of individuals and their progeny are excreted in urine, particularly in immunocompromised patients. JC virus, another human polyomavirus, has been considered to be transmitted from parents to children during prolonged cohabitation. However, BKV has been supposed to be transmitted not only within but also outside the family. In the present study, to clarify this possibility, we analyzed phylogenetically 35 BKV which were excreted in the urine by Japanese children and adults undergoing stem cell transplantation. Subtypes I, III and IV were detected in 15, two and one children and in 15, one and one adults, respectively. Among 15 subtype I isolates from children, three, four and eight belonged to subgroups Ia, Ib-1 and Ic, respectively. All the three children from whom Ia was detected were less than 9 years old. In contrast in the adults, three subtype I belonged to Ib-1 and the other 12 to Ic. These findings may reflect the recent transmission of BKV Ia strains to Japanese children. 相似文献
239.
Seiji Nakamura Toshinari Takamura Naoto Matsuzawa-Nagata Hiroaki Takayama Hirofumi Misu Hiroyo Noda Satoko Nabemoto Seiichiro Kurita Tsuguhito Ota Hitoshi Ando Ken-ichi Miyamoto Shuichi Kaneko 《The Journal of biological chemistry》2009,284(22):14809-14818
Visceral adiposity in obesity causes excessive free fatty acid (FFA) flux
into the liver via the portal vein and may cause fatty liver disease and
hepatic insulin resistance. However, because animal models of insulin
resistance induced by lipid infusion or a high fat diet are complex and may be
accompanied by alterations not restricted to the liver, it is difficult to
determine the contribution of FFAs to hepatic insulin resistance. Therefore,
we treated H4IIEC3 cells, a rat hepatocyte cell line, with a monounsaturated
fatty acid (oleate) and a saturated fatty acid (palmitate) to investigate the
direct and initial effects of FFAs on hepatocytes. We show that palmitate, but
not oleate, inhibited insulin-stimulated tyrosine phosphorylation of insulin
receptor substrate 2 and serine phosphorylation of Akt, through c-Jun
NH2-terminal kinase (JNK) activation. Among the well established
stimuli for JNK activation, reactive oxygen species (ROS) played a causal role
in palmitate-induced JNK activation. In addition, etomoxir, an inhibitor of
carnitine palmitoyltransferase-1, which is the rate-limiting enzyme in
mitochondrial fatty acid β-oxidation, as well as inhibitors of the
mitochondrial respiratory chain complex (thenoyltrifluoroacetone and carbonyl
cyanide m-chlorophenylhydrazone) decreased palmitate-induced ROS
production. Together, our findings in hepatocytes indicate that palmitate
inhibited insulin signal transduction through JNK activation and that
accelerated β-oxidation of palmitate caused excess electron flux in the
mitochondrial respiratory chain, resulting in increased ROS generation. Thus,
mitochondria-derived ROS induced by palmitate may be major contributors to JNK
activation and cellular insulin resistance.Insulin is the major hormone that inhibits gluconeogenesis in the liver.
Visceral adiposity in obesity causes hepatic steatosis and insulin resistance.
In an insulin-resistant state, impaired insulin action allows enhancement of
glucose production in the liver, resulting in systemic hyperglycemia
(1) and contributing to the
development of type 2 diabetes. In addition, we have demonstrated
experimentally that insulin resistance accelerated the pathology of
steatohepatitis in genetically obese diabetic OLETF rats
(2). In contrast, lipid-induced
oxidative stress caused steatohepatitis and hepatic insulin resistance in mice
(3). In fact, steatosis of the
liver is an independent predictor of insulin resistance in patients with
nonalcoholic fatty liver disease
(4).It remains unclear whether hepatic steatosis causally contributes to
insulin resistance or whether it is merely a resulting pathology. Excessive
dietary free fatty acid
(FFA)2 flux into the
liver via the portal vein may cause fatty liver disease and hepatic insulin
resistance. Indeed, elevated plasma FFA concentrations correlate with obesity
and decreased target tissue insulin sensitivity
(5).Experimentally, lipid infusion or a high fat diet that increases
circulating FFA levels promotes insulin resistance in the liver. Candidate
events linking FFA to insulin resistance in vivo are the
up-regulation of SREBP-1c (6),
inflammation caused by activation of c-Jun amino-terminal kinase (JNK)
(7) or IKKβ
(8), endoplasmic reticulum (ER)
stress (9), ceramide
(10,
11), and TRB3
(12).However, which event is the direct and initial target of FFA in the liver
is unclear. Insulin resistance induced by lipid infusion or a high fat diet is
complex and may be accompanied by alterations not restricted to the liver,
making it difficult to determine the contribution of FFAs to hepatic insulin
resistance. For example, hyperinsulinemia and hyperglycemia secondary to the
initial event also may contribute to the development of diet-induced insulin
resistance in vivo
(6).To address the early event(s) triggering the development of high fat diet-
or obesity-induced insulin resistance, we investigated the molecular
mechanism(s) underlying the direct action of FFA on hepatocytes to cause
insulin resistance in vitro, using the rat hepatocyte cell line
H4IIEC3. We found that mitochondria-derived reactive oxygen species (ROS) were
a cause of palmitate-induced insulin resistance in hepatocytes. 相似文献
240.
Shin-ichi J. Takayama Kiyofumi Irie Hulin Tai Takumi Kawahara Shun Hirota Teruhiro Takabe Luis A. Alcaraz Antonio Donaire Yasuhiko Yamamoto 《Journal of biological inorganic chemistry》2009,14(6):821-828
Electron transfer (ET) through and between proteins is a fundamental biological process. The activation energy for an ET reaction
depends upon the Gibbs energy change upon ET (ΔG
0) and the reorganization energy. Here, we characterized ET from Pseudomonas aeruginosa cytochrome c
551 (PA) and its designed mutants to cupredoxins, Silene pratensis plastocyanin (PC) and Acidithiobacillus ferrooxidans rusticyanin (RC), through measurement of pseudo-first-order ET rate constants (k
obs). The influence of the ΔG
0 value for ET from PA to PC or RC on the k
obs value was examined using a series of designed PA proteins exhibiting a variety of E
m values, which afford the ΔG
0 variation range of 58–399 meV. The plots of the k
obs values obtained against the ΔG
0 values for both PA–PC and PA–RC redox pairs could be fitted well with a single Marcus equation. We have shown that the ET
activity of cytochrome c can be controlled by tuning the E
m value of the protein through the substitution of amino acid residues located in hydrophobic-core regions relatively far from
the redox center. These findings provide novel insights into the molecular design of cytochrome c, which could be utilized for controlling its ET activity by means of protein engineering.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献