首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
2.
The nuclear factor κB (NF-κB) has been evolutionary conserved from insects to mammals and plays a major regulatory role in the initiation of physiological responses. In this study, we identified and characterized a primitive and functional NF-κB pathway active in the immune defence of the sea cucumber (Apostichopus japonicus). The ancient NF-κB homologues, Aj-rel and Aj-p105, share numerous signature motifs with their vertebrate orthologues, notably the Rel Homology Domain, Rel Protein Signature DNA Binding Motif, Nuclear Localization Signal and the Ankyrin Repeats for Aj-p105. Phylogenetic analyses indicate that these homologues belong to class I and II of NF-κB respectively. We examined the dimerization of Aj-rel and Aj-p105 and our results demonstrated that Aj-rel forms heterdimers with Aj-p105 and the degradation product of Aj-p105, namely Aj-p50. We further observed that LPS stimulation led to the degradation of Aj-p105 and the nuclear translocation of Aj-rel and Aj-p50. Taken together, our data indicate that the NF-κB signaling cascade is active in sea cucumber and plays a crucial role in regulating their immune defence. Our results increase the available information on sea cucumber immunity and provide new information for use in the study of the comparative and evolutionary aspects of immunity.  相似文献   

3.
In the Candida antarctica lipase B-catalyzed hydrolysis of (R,S)-azolides derived from (R,S)-N-protected proline in water-saturated methyl tert-butyl ether (MTBE), high enzyme activity with excellent enantioselectivity (V S V R ?1 ?>?100) for (R,S)-N-Cbz-proline 1,2,4-triazolide (1) and (R,S)-N-Cbz-proline 4-bromopyrazolide (2) was exploited in comparison with their corresponding methyl ester analog (3). Changing of the substrate structure, water content, solvent, and temperature was found to have profound influences on the lipase performance. On the basis of enzyme activity and enantioselectivity and solvent boiling point, the best reaction condition of using 1 as the substrate in water-saturated MTBE at 45 °C was selected and further employed for the successful resolution of (R,S)-N-Cbz-pipecolic 1,2,4-triazolide (5) and (R,S)-N-Boc-nipecotic 1,2,4-triazolide (9). Moreover, more than 89.1 % recovery of remained (R)-1 is obtainable in five cycles of enzyme reusage, when pH 7 phosphate buffers were employed as the extract at 4 °C.  相似文献   

4.
Conversion of lactose into ethyl acetate by Kluyveromyces marxianus allows economic reuse of whey-borne sugar. The high volatility of ethyl acetate enables its process-integrated recovery by stripping. This stripping is governed by both the aeration rate and the partition coefficient, K EA,L/G. Cultivation at elevated temperatures should decrease the K EA,L/G value and thus favor stripping. K. marxianus DSM 5422 as a potent producer of ethyl acetate was cultivated aerobically in whey-borne media for studying temperature-dependent growth and ester formation. Shake flask cultivation proved thermal tolerance of this yeast growing from 7 to 47 °C with a maximum rate of 0.75 h?1 at 40 °C. The biomass yield was 0.41 g/g at moderate temperatures while low and high temperatures caused distinct drops. The observed μ-T and Y X/S-T dependencies were described by mathematical models. Further cultivations were done in an 1-L stirred reactor for exploring the effect of temperature on ester synthesis. Cultivation at 32 °C caused significant ester formation (Y EA/S?=?0.197 g/g) while cultivation at 42 °C suppressed ester synthesis (Y EA/S?=?0.002 g/g). The high temperature affected metal dissolution from the bioreactor delivering iron for yeast growth and preventing ester synthesis. Cultivation at 32 °C with a switch to 42 °C at the onset of ester synthesis allowed quick and efficient ester production (Y EA/S?=?0.289 g/g). The high temperature lowered the K EA,L/G value from 78 to 44 L/L which heightened the gas-phase ester concentration (favoring ester recovery) without increasing the liquid-phase concentration (avoiding product inhibition).  相似文献   

5.
Two native epoxide hydrolases (EHs) were previously discovered from mung bean powder (Vigna radiata), both of which can catalyze the enantioconvergent hydrolysis of p-nitrostyrene oxide (pNSO). In this study, the encoding gene of VrEH1 was successfully cloned from the cDNA of V. radiata by RT-PCR and rapid amplification of cDNA ends (RACE) technologies. High homologies were found to two putative EHs originated from Glycine max (80 %) and Medicago truncatula (79 %). The vreh1 gene constructed in pET28a(+) vector was then heterologously overexpressed in Escherichia coli BL21(DE3), and the encoded protein was purified to homogeneity by nickel affinity chromatography. It was shown that VrEH1 has an optimum activity at 45 °C and is very thermostable with an inactivation energy of 468 kJ mol-1. The enzyme has no apparent requirement of metal ions for activity, and its activity was strongly inhibited by 1 mM of Ni2+, Cu2+, Fe2+, or Co2+. By adding 0.1 % Triton X-100, the enzyme activity could be significantly increased up to 340 %. VrEH1 shows an unusual ability of enantioconvergent catalysis for the hydrolysis of racemic pNSO, affording (R)-p-nitrophenyl glycol (pNPG). It displays opposite regioselectivity toward (S)-pNSO (83 % to Cα) in contrast to (R)-pNSO (87 % to Cβ). The K M and k cat of VrEH1 were determined to be 1.4 mM and 0.42 s-1 for (R)-pNSO and 5.5 mM and 6.2 s-1 for (S)-pNSO. This thermostable recombinant VrEH1 with enantioconvergency is considered to be a promising biocatalyst for the highly productive preparation of enantiopure vicinal diols and also a good model for understanding the mechanism of EH stereoselectivity.  相似文献   

6.
The structurally related peptides neuropeptide Y (NPY), peptide YY (PYY) and pancreatic polypeptide (PP) are endogenous agonists of the NPY receptor (YR) family, which in humans comprises four functionally expressed subtypes, designated Y1R, Y2R, Y4R and Y5R. Nonpeptide antagonists with high affinity and selectivity have been described for the Y1R, Y2R and Y5R, but such compounds are still lacking for the Y4R. In this work, the structures of the high affinity selective (R)-argininamide-type Y1R antagonists BIBP3226 and BIBO3304 were linked via the guanidine or urea moieties to give homo-dimeric argininamides with linker lengths ranging from 31 to 41 atoms. Interestingly, the twin compounds proved to be by far less selective for the Y1R than the R-configured monovalent parent compounds. The decrease in selectivity ratio was most pronounced for Y1R versus Y4R subtype, resulting in comparable affinities of bivalent ligands for Y1R and Y4R (e.g. UR-MK177 ((R,R)-49): Ki = 230 nM (Y1R) and 290 nM (Y4R)). With a Ki value of 130 nM and a Kb value of 20 nM, UR-MK188 ((R,R)-51) was superior to all Y4R antagonists known to date. The S,S-configured optical antipodes of UR-MK177 and UR-MK188 (UR-MEK381 ((S,S)-49) and UR-MEK388 ((S,S)-51)) were synthesized to investigate the stereochemical discrimination by the different receptor subtypes. Whereas preference for R,R-configured argininamides was characteristic of the Y1R, stereochemical discrimination by the Y4R was not observed. This may pave the way to selective Y4R antagonists.  相似文献   

7.
Serine/threonine protein kinases Aurora A, B, and C play essential roles in cell mitosis and cytokinesis, and a number of Aurora kinase inhibitors have been evaluated in the clinic. Herein we report the synthesis and their antiproliferation of 3,5-disubstituted-2-aminopyrazines as kinases inhibitors. Amongst, 4-((3-amino-6- (3,5-dimethylisoxazol-4-yl)pyrazin-2-yl)oxy)-N-(3-chlorophenyl) benzamide (12Aj) exhibited the strongest antiproliferative activities against U38, HeLa, HepG2 and LoVo cells with IC50 values were 11.5 ± 3.2, 1.34 ± 0.23, 7.30 ± 1.56 and 1.64 ± 0.48 μM, as well as inhibited Aurora A and B with the IC50 values were 90 and 152 nM, respectively. Molecular docking studies indicated that 12Aj appeared to form stable hydrogen bonds with either Aurora A or Aurora B. Furthermore, 12Aj arrested HeLa cell cycle in G2/M phase by regulating protein levels of cyclinB1 and cdc2. In addition, the bioinformatics prediction further revealed that 12Aj possessed good drug likeness using SwissADME. These results suggested that 12Aj was worthy of future development of potent anticancer agents as pan-Aurora kinases.  相似文献   

8.
The Mn4CaO5 cluster of photosystem II (PSII) catalyzes the oxidation of water to molecular oxygen through the light-driven redox S-cycle. The water oxidizing complex (WOC) forms a triad with TyrosineZ and P680, which mediates electrons from water towards the acceptor side of PSII. Under certain conditions two other redox-active components, TyrosineD (YD) and Cytochrome b 559 (Cyt b 559) can also interact with the S-states. In the present work we investigate the electron transfer from Cyt b 559 and YD to the S2 and S3 states at 195 K. First, YD ? and Cyt b 559 were chemically reduced. The S2 and S3 states were then achieved by application of one or two laser flashes, respectively, on samples stabilized in the S1 state. EPR signals of the WOC (the S2-state multiline signal, ML-S2), YD ? and oxidized Cyt b 559 were simultaneously detected during a prolonged dark incubation at 195 K. During 163 days of incubation a large fraction of the S2 population decayed to S1 in the S2 samples by following a single exponential decay. Differently, S3 samples showed an initial increase in the ML-S2 intensity (due to S3 to S2 conversion) and a subsequent slow decay due to S2 to S1 conversion. In both cases, only a minor oxidation of YD was observed. In contrast, the signal intensity of the oxidized Cyt b 559 showed a two-fold increase in both the S2 and S3 samples. The electron donation from Cyt b 559 was much more efficient to the S2 state than to the S3 state.  相似文献   

9.
Elongator proteins comprise six subunits (ELP1–ELP6) and form protein complexes. The elongator protein 2 gene (elp2) encodes a protein with a WD40 repeats domain that acts as a scaffold for complex assembly. It also plays an important role in growth and development. In this study, the full-length cDNA of elongator protein 2 (Ajelp2) was cloned from the sea cucumber Apostichopus japonicus (A. japonicus) using rapid amplification of cDNA ends PCR techniques and comprised 3,058 bp, including a 54 bp 5′ untranslated (UTR), a 526 bp 3′ UTR and a 2,478 bp open reading frame encoding a polypeptide of 825 amino acids. The Ajelp2 sequence showed high homology to 12 other species. The molecular weight and isoelectric of point the presumptive protein were 91.6 kDa and 5.84, respectively. In situ hybridization indicated that the gene is expressed in the body wall, intestine, respiratory tree and longitudinal muscle. The expression level of Ajelp2 increased in recovering of organs in sea cucumber and showed it’s the highest expression level at the 15th day in the intestine and respiratory tree. Its expression then gradually decreased to normal levels. In the body wall, the expression level of Ajelp2 was up-regulated and then down-regulated. These results indicated that Ajelp2 is involved in protein regulation during the regeneration process in the sea cucumber A. japonicus.  相似文献   

10.
Eight mononuclear complexes with multitopic C2-symmetry ligands, [Cu(L)]ClO4, [Mn(L)Cl(H2O)]PF6, (L=N,N′-bis[(S)-prolyl]phenylenediamine (1), N,N′-bis[(S)-N-benzylprolyl]phenylenediamine (2), N,N′-bis{[(S)-pyrrolidin-2-yl]methyl}phenylenediamine (3), N,N′-bis-{[(S)-N-benzyl-pyrrolidin-2-yl]methyl}phenylenediamine (4)) have been prepared and characterised by analytical (elemental analysis, and mass spectroscopy) and FT IR, NMR and electronic spectroscopies. The data show that the ligands are neutral and coordinate to the metal in a tetradentate manner. The N,N′-bis[(S)-prolyl]phenylenediamine ligand also appears as an anionic species, (LH-2), and the single crystal structure determination of the respective complex, [Cu(1)]H2O, is reported. This new family of Cu-complexes catalyse the cyclopropanation of styrene with ethyl and t-butyl diazoacetate to afford cis/trans 2-phenylcyclopropan-1-carboxylates with good yields and selectivity against dimerisation and low ee (<10%). On the other hand, the manganese and copper complexes also catalyse the oxidation of organic sulfides to sulfoxides with high selectivity, and moderate to low enantioselectivity. If an excess of oxidant were used the reaction yields sulfone as only product with excellent yield.  相似文献   

11.
Condensation of (S,S)-1,2-cyclohexanediamine with 2 equiv. of 2-pyridine carboxaldehyde in toluene in the presence of molecular sieves at 70 °C gives N,N′-bis(pyridin-2-ylmethylene)-(S,S)-1,2-cyclohexanediamine (S,S-1) in 95% yield. Reduction of 1 with an excess of NaBH4 in MeOH at 50 °C gives N,N′-bis(pyridin-2-ylmethyl)-(S,S)-1,2-cyclohexanediamine (S,S-2) in 90% yield. Reaction of 1 or 2 with 1 equiv. of CuCl2 · 2H2O in methanol gives complexes [N-(pyridin-2-ylmethylene)-(S,S)-1,2-cyclohexanediamine]CuCl2 (3) and [Cu(S,S-2)(H2O)]Cl2 · H2O (4), respectively, in good yields. Complex 4 can further react with 1 equiv. of CuCl2 · 2H2O in methanol to give [Cu(S,S-2)][CuCl4] (5) in 75% yield. The rigidity of the ligand coupled with the steric effect of the free anion plays an important role in the formation of the helicates. Treatment of ligand S,S-1 with AgNO3 induces a polymer helicate {[Ag(S,S-1)][NO3]}n (6), while reaction of ligand 2 with AgPF6 or AgNO3 in methanol affords a mononuclear single helicate [Ag(S,S-2)][PF6] (7) or a dinuclear double helicate [Ag2(S,S-2)2][NO3]2 · 2CH3OH (8) in good yields, respectively. All compounds have been characterized by various spectroscopic data and elemental analyses. Compounds 1, 3-5, 7 and 8 have been further subjected to single-crystal X-ray diffraction analyses. The Cu(II) complexes do not show catalytic activity for allylation reaction, in contrast to Ag(I) complexes, but they do show catalytic activity for Henry reaction (nitroaldol reaction) that Ag(I) complexes do not.  相似文献   

12.
A real-time quantitative polymerase chain reaction (QPCR) was used to evaluate biokinetic coefficients of Nitrosomonas nitrosa and N. cryotolerans clusters growing simultaneously in a batch mode of ammonia oxidation. The mathematical models based on Monod equation were employed to describe the competitive relationship between these clusters and were fitted to experimental data to obtain biokinetic values. The maximum growth rates (μ m), half-saturation coefficients (K S), microbial yields (Y) and decay coefficients (k d) of N. nitrosa and N. cryotolerans were 1.77 and 1.21 day?1, 23.25 and 23.06 mg N·L?1, 16 × 108 and 1 × 108 copies·mg N?1, 0.26 and 0.20 day?1, respectively. The estimated coefficients were applied for modeling continuous operations at various hydraulic retention times (HRTs) with an influent ammonia concentration of 300 mg N·L?1. Modeling results revealed that ammonia oxidation efficiencies were achieved 55–98 % at 0.8–10 days HRTs and that the system was predicted to be washed out at HRT of 0.7 days. Overall, use of QPCR for estimating biokinetic coefficients of the two AOB cluster growing simultaneously by use of ammonia were successful. This idea may open a new direction towards biokinetics of ammonia oxidation in which respirometry tests are usually employed.  相似文献   

13.
The temperature dependence of donor side reactions was analysed within the framework of the Marcus theory of nonadiabatic electron transfer. The following results were obtained for PS II membrane fragments from spinach: (1) the reorganisation energy of P680+? reduction by YZ is of the order of 0.5?eV in samples with a functionally fully competent water oxidising complex (WOC); (2) destruction of the WOC by Tris-washing gives rise to a drastic increase of λ to values of the order of 1.6?eV; (3) the reorganisation energies of the oxidation steps in the WOC are dependent, on the redox states S i with values of about 0.6?eV for the reactions YZ OX S 0→YZ S 1 and YZ OX S 1→YZ S 2, 1.6?eV for the reaction YZ OX S 2→YZ S 3 and 1.1?eV (above a characteristic temperature uc of about 6??°C) for the reaction YZ OX S 3→→YZ S 0+O2. Using an empirical rate constant-distance relationship, the van der Waals distance between YZ and P680 was found to be about 10?Å, independent of the presence or absence of the WOC, whereas the distance between YZ and the manganese cluster in the WOC was ≥15?Å. Based on the calculated activation energies the environment of YZ is inferred to be almost "dry" and hydrophobic when the WOC is intact but becomes enriched with water molecules after WOC destruction. Furthermore, it is concluded that the transition S 2S 3 is an electron transfer reaction gated by a conformational change, i.e. it comprises significant structural changes of functional relevance. Measurements of kinetic H/D isotope exchange effects support the idea that none of these reactions is gated by the break of a covalent O-H bond. The implications of these findings for the mechanism of water oxidation are discussed.  相似文献   

14.
Biodegradation of pyridine by a novel bacterial strain, Rhizobium sp. NJUST18, was studied in batch experiments over a wide concentration range (from 100 to 1,000 mg l?1). Pyridine inhibited both growth of Rhizobium sp. NJUST18 and biodegradation of pyridine. The Haldane model could be fitted to the growth kinetics data well with the kinetic constants μ* = 0.1473 h?1, K s = 793.97 mg l?1, K i = 268.60 mg l?1 and S m = 461.80 mg l?1. The true μ max, calculated from μ*, was found to be 0.0332 h?1. Yield coefficient Y X/S depended on S i and reached a maximum of 0.51 g g?1 at S i of 600 mg l?1. V max was calculated by fitting the pyridine consumption data with the Gompertz model. V max increased with initial pyridine concentration up to 14.809 mg l?1 h?1. The q S values, calculated from $V_{ \hbox{max} }$ , were fitted with the Haldane equation, yielding q Smax = 0.1212 g g?1 h?1 and q* = 0.3874 g g?1 h?1 at S m′ = 507.83 mg l?1, K s′ = 558.03 mg l?1, and K i′ = 462.15 mg l?1. Inhibition constants for growth and degradation rate value were in the same range. Compared with other pyridine degraders, μ max and S m obtained for Rhizobium sp. NJUST18 were relatively high. High K i and K i′ values and extremely high K s and K s′ values indicated that NJUST18 was able to grow on pyridine within a wide concentration range, especially at relatively high concentrations.  相似文献   

15.
Mollusks lack an adaptive immune system and rely solely on the innate immune response. The nuclear factor-kappa B (NF-κB) signaling pathway is one of the most important components of the innate immune system and its activity is regulated by physical interaction with the inhibitor of NF-κB (IκB) protein. The manila clam, Ruditapes philippinarum (Rp), is a key species of the world’s aquaculture industry, and recent pathogenic threats, such as the Gram-negative lipopolysaccharide (LPS)-expressing Vibrio tapetis bacteria, have produced severe adverse economic impacts. Here, we describe identification, characterization and immune responses of novel IκB (Rp-IκB) in the manila clam. The Rp-IκB cDNA is comprised of a 1,032 bp open reading frame, which encodes 343 amino acid residues and has a predicted molecular mass of 38 kDa. The Rp-IκB protein exhibits typical structural features of IκB family members, including the IκB degradation motif, PEST sequence, and six ankyrin repeats. Phylogenetic analysis showed that manila clam and other known molluscan IκB proteins grouped together in the invertebrate cluster. Analysis of the tissue expression distribution revealed that Rp-IκB was ubiquitously expressed. However, immune challenge with V. tapetis and purified LPS endotoxin induced significant up-regulation of Rp-IκB expression in gill and hemocytes. These results indicated that Rp-IκB may play an important role in manila clam defense against bacterial infection.  相似文献   

16.
Thiourea, PhNHC(S)NHP(O)(OPri)2 (LH) chelates of CoII, NiII, and PdII ions have been obtained and investigated by single-crystal X-ray diffraction, UV, IR, NMR spectroscopy, and EI mass-spectrometry. The unusual 1,3-N,S-coordination via sulfur and NP(O) nitrogen atoms has been found in the trans-square-planar NiL2 and PdL2 complexes, whereas the 1,5-O,S-coordination is realized in the tetrahedral CoL2 complex. DFT calculations have revealed significant stabilization of the 1,3-N,S-structures due to stronger crystal field and the NH-OP hydrogen bonds.  相似文献   

17.
Two new pterosin glycosides, (2S,3S)-pterosin C 3-O-β-d-(4′-(E)-caffeoyl)-glucopyranoside (1) and (2S,3S)-pterosin C 3-O-β-d-(6′-(E)-p-coumaroyl)-glucopyranoside (2), were isolated from Pteris multifida (Pteridaceae) roots along with ten known pterosin compounds (312). The chemical structures of the isolated compounds were elucidated by extensive analysis of the 1D, 2D NMR, HRESIMS, and CD spectroscopic data. The cytotoxicities of 112 against HCT116 human colorectal cancer cell line were evaluated. Among the isolates, compound 1 showed moderate antiproliferative activity in HCT116 cells with an IC50 value of 8.0 ± 1.7 μM. Additionally, 1 induced the upregulation of the caspase-9 and procaspase-9 levels in Western blots and increased the annexin V/propidium iodide (PI)-positive cell population in flow cytometry.  相似文献   

18.
19.
The objective of this study was to evaluate ethanol production and bioadsorption with four red seaweeds, Gelidium amansii, Gracilaria verrucosa, Kappaphycus alvarezii and Eucheuma denticulatum. To produce ethanol, thermal acid hydrolysis, enzymatic saccharification and fermentation was carried out. After pretreatment, 38.5, 39.9, 31.0 and 27.5 g/L of monosaccharides were obtained from G. amansii, G. verrucosa, K. alvarezii and E. denticulatum, respectively. Ethanol fermentation was performed with Saccharomyces cerevisiae KCCM 1129 adapted to 80 g/L galactose. The ethanol productions by G. amansii, G. verrucosa, K. alvarezii and E. denticulatum were 18.8 g/L with Y EtOH = 0.49, 19.1 g/L with Y EtOH = 0.48, 14.5 g/L with Y EtOH = 0.47 and 13.0 g/L with Y EtOH = 0.47, respectively. The waste seaweed slurries after the ethanol fermentation were reused to adsorb Cd(II), Pb(II) and Cu(II). Using langmuir isotherm model, Cu(II) had the highest affinity for waste seaweeds with the highest q max and electronegativity values among three heavy metals.  相似文献   

20.
A Gram-negative, aerobic, non-flagellated, non-gliding, rod-shaped bacterial strain, designated WR-R1YT, was isolated from soil at a field of reeds in South Korea. Strain WR-R1YT grew optimally at 30 °C, at pH 7.0–7.5 and in the absence of NaCl. Neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain WR-R1YT fell within the clade comprising Mucilaginibacter species, coherently clustering with the type strain of Mucilaginibacter composti, with which it exhibited the highest 16S rRNA gene sequence similarity value of 97.6 %. Sequence similarities to the type strains of the other Mucilaginibacter species and the other species used in the phylogenetic analysis were 93.1–96.9 % and <91.1 %, respectively. Strain WR-R1YT contained MK-7 as the predominant menaquinone and iso-C15:0, summed feature 3 (C16:1 ω6c and/or C16:1 ω7c), C16:0 and iso-C17:0 3-OH as the major fatty acids. The major polar lipids were phosphatidylethanolamine and one unidentified aminophospholipid. The DNA G+C content of strain WR-R1YT was 43.1 mol% and its mean DNA–DNA relatedness value with M. composti KACC 14956T was 17 %. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain WR-R1YT is separate from other Mucilaginibacter species. On the basis of the data presented, strain WR-R1YT represents a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter calamicampi sp. nov. is proposed. The type strain is WR-R1YT (= KCTC 32214T = CCUG 63418T).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号