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The three-substituted dipyridyl ligand bis(3-pyridylmethyl)sulfide (L1) was prepared by the reaction of 3-(chloromethyl)pyridine hydrochloride with thioacetamide under basic conditions. L1 was reacted with CuI to give complexes with 1:2 and 1:1 molar ratios. Crystal structures of [(CuI)2(L1)]∞ (1) and [CuI(L1)]∞ (2) were determined. In complex 1 the CuI species formed a one-dimensional staircase polymer to which L1 was bound in a side-by-side fashion with π-π interactions between the ligands on each side. Complex 2 consisted of a one-dimensional ribbon polymer of metallomacrocycles formed from two L1 ligands bridging Cu2I2 dimers which were fused within the macrocyclic ring. The analogous disulfide ligand bis(3-pyridylmethyl)disulfide (L2) was prepared by oxidation of the corresponding thiol 3-(sulfanylmethyl)pyridine. L2 was reacted with CuI in 1:2 and 1:1 molar ratios and products isolated but only the 1:1 product was able to be crystallised. The crystal structure of [CuI(L2)]∞ (3) consisted of a one-dimensional ribbon polymer of metallomacrocycles formed from two L2 ligands linked through Cu2I2 dimers. The difference in the metallomacrocycle linking between the related structures 2 and 3 was attributed to the difference in ligand conformation. 相似文献
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Chun-Sen Liu 《Inorganica chimica acta》2007,360(8):2532-2540
In our efforts to investigate the factors that affect the formation of coordination architectures, such as secondary coordination donors and pendant skeletons of the carboxylic acid ligands, as well as H-bonding and other weak interactions, two kinds of ligands: (a) 3-(2-pyridyl)pyrazole (L1) with a non-coordinated N atom as a H-bonding donor, a 2,2′-bipyridyl-like chelating ligand, and (b) four carboxylic ligands with different secondary coordination donors and/or pendant skeletons, 1,4-benzenedicarboxylic acid (H2L2), 4-sulfobenzoic acid (H2L3), quinoline-4-carboxylic acid (HL4) and fumaric acid (H2L5), have been selected to react with Mn(II) salts, and five new complexes, [Mn(L1)2(SO4)]2 (1), [Mn(L1)2(L2)]∞ (2), [Mn(L1)(HL3)2]∞ (3), Mn(L1)2(L4)2 (4), and [Mn(L1)2(L5)]∞ (5), have been obtained and structurally characterized. The structural differences of 1-5 can be attributed to the introduction of the different carboxylic acid ligands (H2L2, H2L3, HL4, and H2L5) with different secondary coordination donors and pendant skeletons, respectively. This result also reveals that the typical H-bonding (i.e. N-H?O and O-H?O) and some other intra- or inter-molecular weak interactions, such as C-H?O weak H-bonding and π?π interactions, often play important roles in the formation of supramolecular aggregates, especially in the aspect of linking the multi-nuclear discrete subunits or low-dimensional entities into high-dimensional supramolecular networks. 相似文献
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Xunyan Dong Yue Zhao Jianxun Zhao Xiaoyuan Wang 《Journal of industrial microbiology & biotechnology》2016,43(6):873-885
Previously we have characterized a threonine dehydratase mutant TDF383V (encoded by ilvA1) and an acetohydroxy acid synthase mutant AHASP176S, D426E, L575W (encoded by ilvBN1) in Corynebacterium glutamicum IWJ001, one of the best l-isoleucine producing strains. Here, we further characterized an aspartate kinase mutant AKA279T (encoded by lysC1) and a homoserine dehydrogenase mutant HDG378S (encoded by hom1) in IWJ001, and analyzed the consequences of all these mutant enzymes on amino acids production in the wild type background. In vitro enzyme tests confirmed that AKA279T is completely resistant to feed-back inhibition by l-threonine and l-lysine, and that HDG378S is partially resistant to l-threonine with the half maximal inhibitory concentration between 12 and 14 mM. In C. glutamicum ATCC13869, expressing lysC1 alone led to exclusive l-lysine accumulation, co-expressing hom1 and thrB1 with lysC1 shifted partial carbon flux from l-lysine (decreased by 50.1 %) to l-threonine (4.85 g/L) with minor l-isoleucine and no l-homoserine accumulation, further co-expressing ilvA1 completely depleted l-threonine and strongly shifted carbon flux from l-lysine (decreased by 83.0 %) to l-isoleucine (3.53 g/L). The results demonstrated the strongly feed-back resistant TDF383V might be the main driving force for l-isoleucine over-synthesis in this case, and the partially feed-back resistant HDG378S might prevent the accumulation of toxic intermediates. Information exploited from such mutation-bred production strain would be useful for metabolic engineering. 相似文献
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Jiandong Zhang Zhimei Cui Honghong Chang Xiaojun Fan Qiuyong Zhao Wenlong Wei 《Biotechnology letters》2016,38(9):1559-1564
Objectives
To investigate the efficiency of a cofactor regeneration enzyme co-expressed with a glycerol dehydrogenase for the production of 1,3-dihydroxyacetone (DHA).Results
In vitro biotransformation of glycerol was achieved with the cell-free extracts containing recombinant GlyDH (glycerol dehydrogenase from Escherichia coli), LDH (lactate dehydrogenase form Bacillus subtilis) or LpNox1 (NADH oxidase from Lactobacillus pentosus), giving DHA at 1.3 g l?1 (GlyDH/LDH) and 2.2 g l?1 (GlyDH/LpNox1) with total turnover number (TTN) of NAD+ recycling of 6039 and 11100, respectively. Whole cells of E. coli (GlyDH–LpNox1) co-expressing both GlyDH and LpNox1 were constructed and converted 10 g glycerol l?1 to DHA at 0.2–0.5 g l?1 in the presence of zero to 2 mM exogenous NAD+. The cell free extract of E. coli (GlyDH–LpNox) converted glycerol (2–50 g l?1) to DHA from 0.5 to 4.0 g l?1 (8–25 % conversion) without exogenous NAD+.Conclusions
The disadvantage of the expensive consumption of NAD+ for the production of DHA has been overcome.9.
Yuya Takahashi Xianghua Li Chigen Tsukamoto Kejing Wang 《Molecular breeding : new strategies in plant improvement》2018,38(7):93
Group A saponins are thought to be the cause of bitter and astringent tastes in processed foods of soybean (Glycine max), and the elimination of group A saponins is an important breeding objective. The group A saponins include two main Aa and Ab types, controlled by codominant alleles at the Sg-1 locus that is one of several key loci responsible for saponin biosynthesis in the subgenus Glycine soja. However, A0 mutant lacking group A saponin is a useful gene resource for soybean quality breeding. Here, eight Chinese wild soybean A0 accessions were sequenced to reveal the mutational mechanisms, and the results showed that these mutants were caused by at least three kinds of mechanisms involving four allelic variants (sg-10-b2, sg-10-b3, Sg-1b-0, and Sg-1b-01). The sg-10-b2 had two nucleotide deletions at positions +?72 and +?73 involving in the 24th and 25th amino acids. The sg-10-b3 contained a stop codon (TGA) at the 254th residue. The Sg-1b-0 and Sg-1b-01 were two novel A0-type mutants, which likely carried normal structural alleles, and nevertheless did not encode group A saponin due to unknown mutations beyond the normal coding regions. In addition, to reveal the structural features, allelic polymorphism, and mechanisms of the abiogenetic absence of group A (i.e., A0 phenotype), nucleotide sequence analysis was performed for the Sg-1 locus in wild soybean (Glycine soja). The results showed that Sg-1 alleles had a lower conservatism in the coding region; as high as 18 sequences were found in Chinese wild soybeans in addition to the Sg-1a (Aa) and Sg-1b (Ab) alleles. Sg-1a and Sg-1b alleles were characterized by eight synonymous codons and nine amino acid substitutions. Two evolutionarily transitional allelic sequences (Sg-1a7 and Sg-1b2) from Sg-1a toward Sg-1b were detected. 相似文献
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Dr. H. Cruse 《Biological cybernetics》1972,11(4):185-200
- Form discrimination by honeybees can be measured when individuals are trained to select a rewarded shape in preference to other, unrewarded ones (Table 2). In these experiments, the values of discrimination for some pairs of shapes depend upon which of the pair is rewarded (“symmetrical, asymmetrical discrimination”, Table 3, 4).
- Two groups of possible mechanisms of form discrimination will be discussed. Experimental findings preclude the exclusive use by the bees of any one of those mechanisms. The following discrimination function, however, describes the present as well as previously reported results: $$U = \left| {C_{\text{1}} \frac{{R^ + + R^ - }}{G}F^ + + C_2 {\text{(log}}K^ + {\text{ - log}}K^ - {\text{)}}} \right|$$ (Figs. 4, 5, 7, 8, 9, 10). R +, R ?, G and F + are parts of areas (Fig. 1), K + and K ? contour lengths of the shapes to be compared.
- The weighting factors, C 1 and C 2, are apparently given different values by the bee for different shape combinations. Some results might support Mazochin-Porshnyakov's (1969) hypothesis that bees can also recognize other features of the shapes, according to the problem to be solved (Sect. D).
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In order to further understand the coordination chemistry of diazamesocyclic systems, a series of mononuclear NiII complexes with 1,4-diazacycloheptane (DACH) functionalized by additional imidazole or pyridine donor pendants, including [NiL1](ClO4)2 · H2O (1), [NiL1Cl](ClO4) (2), [NiL2Cl](ClO4) · CH3OH (3), [NiL2Cl][NiL2](ClO4)3 (4) and [NiL3](ClO4)2 (5), where L1 = 1,4-bis(N-1-methylimidazol-2-yl-methyl)-1,4-diazacycloheptane, L2 = 1,4-bis(pyridyl-2-yl-methyl)-1,4-diazacycloheptane, and L3 = 1,4-bis-(imidazol-4-yl-methyl)-1,4-diazacycloheptane, have been prepared and characterized. A detailed study on the solid structures and solution spectra of these complexes indicates that tetradentate ligands L1, L2 and L3 would lead to new NiII complexes with different coordination environments in the solid states and solution. The N-methyl substituted imidazole functionalized ligand L1 forms green compound 2 and yellow product 1; while the pyridine functionalized ligand L2 affords red product 4 and green complex 3; the ligand L3 results in only one stable mononuclear NiII product 5. The solution behaviors of these interesting compounds were also investigated by UV-Vis technique. 相似文献
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The effects of genotype of the laboratory strains, C(1)DX, ywf/Y, 23.5 MRF/CyL 4, and C(1)DX,yf; π2, on locus-specific instability in the yellow gene of the strains y 2-217, y 2-715, and y 2-700 from Uman’ population of Drosophila melanogaster was studied. Crosses of the males from Uman’-derived lines with the C(1)DX,ywf/Y females yielded a cascade of derivatives, mostly consisting of y + and y 2 alleles, while their crosses with the 23.5 MRF/CyL 4 and C(1)DX,yf; π2 females mostly resulted in the appearance of y + and y 1 derivatives. The genomes of laboratory strains used in the study contained the full-sized hobo elements, which could differ from one another relative to the structure of variable region and affinity to different DNA sequences. 相似文献
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Hua Zhang Priyam Jani Tian Liang Yongbo Lu Chunlin Qin 《Journal of molecular histology》2017,48(2):83-98
Bone morphogenetic protein 1 (BMP1) and tolloid-like 1 (TLL1) belong to the BMP1/tolloid-like proteinase family, which cleaves secretory proteins. The constitutive deletion of the Bmp1 or Tll1 genes causes perinatal or embryonic lethality in mice. In this study, we first studied the β-galactosidase activity in mice in which an IRES-lacZ-Neo cassette was inserted in the intron of either the Bmp1 or the Tll1 gene; the β-galactosidase activities were used to reflect the expression of endogenous Bmp1 and Tll1, respectively. Our X-gal staining results showed that the odontoblasts in the tooth and cells in the periodontal ligament express both Bmp1 and Tll1. We then created Bmp1 flox/flox and Tll1 flox/flox mice by removing the IRES-lacZ-Neo cassette. By breeding 2.3 kb Col1a1-Cre mice with the Bmp1 flox/flox and Tll1 flox/flox mice, we further generated Col1a1-Cre;Bmp1 flox/flox ;Tll1 flox/flox mice in which both Bmp1 and Tll1 were inactivated in the Type I collagen-expressing cells. We employed X-ray radiography, histology and immunohistochemistry approaches to characterize the Col1a1-Cre;Bmp1 flox/flox ;Tll1 flox/flox mice. Our results showed that the molars of the Col1a1-Cre;Bmp1 flox/flox ;Tll1 flox/flox mice had wider predentin, thinner dentin and larger pulp chambers than those of the normal controls. The dentinal tubules of the molars in the Col1a1-Cre;Bmp1 flox/flox ;Tll1 flox/flox mice appeared disorganized. The level of dentin sialophosphoprotein in the molars of the 6-week-old Col1a1-Cre;Bmp1 flox/flox ;Tll1 flox/flox mice was lower than in the normal controls. The periodontal ligaments of the Col1a1-Cre;Bmp1 flox/flox ;Tll1 flox/flox mice were disorganized and had less fibrillin-1. Our findings indicate that the proteinases encoded by Bmp1 and Tll1 genes play essential roles in the development and maintenance of mouse dentin and periodontal ligaments. 相似文献
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Bartolomeu Nascimento Jeannie Callum Homer Tien Gordon Rubenfeld Ruxandra Pinto Yulia Lin Sandro Rizoli 《CMAJ》2013,185(12):E583-E589
Background:
Hemorrhage coupled with coagulopathy remains the leading cause of preventable in-hospital deaths among trauma patients. Use of a transfusion protocol with a predefined ratio of 1:1:1 (1 each of red blood cells [RBC], frozen plasma [FP] and platelets) has been associated with improved survival in retrospective studies in military and civilian settings, but such a protocol has its challenges and may increase the risk of respiratory complications. We conducted a randomized controlled trial to assess the feasibility of a 1:1:1 transfusion protocol and its effect on mortality and complications among patients with severe trauma.Methods:
We included 78 patients seen in a tertiary trauma centre between July 2009 and October 2011 who had hypotension and bleeding and were expected to need massive transfusion (≥ 10 RBC units in 24 h). We randomly assigned them to either the fixed-ratio (1:1:1) transfusion protocol (n = 40) or to a laboratory-results–guided transfusion protocol (control; n = 38). The primary outcome, feasibility, was assessed in terms of blood product ratios and plasma wastage. Safety was measured based on 28-day mortality and survival free of acute respiratory distress syndrome.Results:
Overall, a transfusion ratio of 1:1:1 was achieved in 57% (21/37) of patients in the fixed-ratio group, as compared with 6% (2/32) in the control group. A ratio of 1:1 (RBC:FP) was achieved in 73% (27/37) in the fixed-ratio group and 22% (7/32) in the control group. Plasma wastage was higher with the intervention protocol (22% [86/390] of FP units v. 10% [30/289] in the control group). The 28-day mortality and number of days free of acute respiratory distress syndrome were statistically similar between the groups.Interpretation:
The fixed-ratio transfusion protocol was feasible in our study, but it was associated with increased plasma wastage. Larger randomized trials are needed to evaluate the efficacy of such a protocol in trauma care. Trial registration: ClinicalTrials.gov, no. A fixed-ratio (1:1:1) transfusion strategy is a resuscitation strategy for trauma patients that promotes the transfusion of red blood cells (RBC), plasma and platelets (PLT) at a 1:1:1 ratio while minimizing crystalloid infusion. NCT009455421 This balanced transfusion strategy aims to correct both the early coagulopathy of trauma and the volume status of patients in hemorrhagic shock, thus targeting preventable hemorrhage-related deaths.2,3 Retrospective studies of the 1:1:1 transfusion protocol reported marked reductions in mortality based on retrospectively calculated ratios of plasma:PLT:RBC.4–6 Methodologic limitations, particularly survivorship bias (where higher mortality was associated with low ratios of plasma and PLT to RBC in unsalvageable patients who died before 1:1:1 transfusion could be achieved), preclude any definitive conclusion on the potential benefit of a 1:1:1 transfusion strategy in terms of efficacy and safety.7–10The 1:1:1 transfusion strategy has been widely adopted by trauma centres worldwide11,12 and is being increasingly used in prehospital care and in the care of patients without traumatic injuries.13–15 Widespread adoption of the strategy has significant resource and safety implications. Its full implementation requires access to thawed type AB plasma, which is chronically in short supply.16 In addition, because of the difficulty in predicting the need for massive transfusion (commonly defined as ≥ 10 RBC units in 24 h), the 1:1:1 transfusion protocol may lead to unnecessary exposure to blood components and an increased risk of acute respiratory distress syndrome, sepsis and multiple organ dysfunction.17We conducted a pilot randomized controlled trial comparing a 1:1:1 transfusion strategy with the standard of care at our institution (laboratory-results–guided transfusion; laboratory results are available for transfusion decisions throughout resuscitation) in trauma patients predicted to need massive transfusion. Our primary objective was to assess the feasibility and safety of the fixed-ratio protocol in patients with severe trauma. 相似文献16.
Dipankar Maity W.S. Sheldrick Bilwadal Bandyopadhyay 《Inorganica chimica acta》2006,359(10):3197-3204
Synthesis and single crystal X-ray structures of H2L1 and VO(L1)(HL) [H2L1 = N,N-bis(2-hydroxy-3,5-ditertiarybutyl)-N′,N′-dimethylethylendiamine) or simply aminebis(phenol) and H2L = salicylic acid) are reported here. The complex [VO(L1)(HL)] is in distorted octahedral geometry under O4N2 donor environment where the basal core is defined by O(1), O(3), O(2) and N(5) atoms and two axial coordinates are occupied by O(4), an alkoxo-group and N(1), an imino-nitrogen atom. The electron spray mass spectrometric study on [VO(L1)(HL)] in MeCN clearly points out the existence of single species in solution. Again, the 51V NMR of the bulk polycrystalline sample reveals that the complex [VO(L1)(HL)] mainly exists in three out of four possible isomers. The formation of [VO(L1)(HL)] from both [VO(L1)(OMe)] and [VO(L1)(OEt)] was followed kinetically by reacting with salicylic acid in MeCN. The presence of isosbestic point indicates a clean conversion of the reactants to product. 相似文献
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L M Silva M C Silva S M F A Silva R C Alves H A A Siqueira E J Marques 《Neotropical Entomology》2018,47(2):292-301
Bacillus thuringiensis (Berliner) bears essential characteristics in the control of insect pests, such as its unique mode of action, which confers specificity and selectivity. This study assessed cry gene contents from Bt strains and their entomotoxicity against Diatraea saccharalis (F.) and Diatraea flavipennella (Box) (Lepidoptera: Crambidae). Bioassays with Bt strains were performed against neonates to evaluate their lethal and sublethal activities and were further analyzed by PCR, using primers to identify toxin genes. For D. saccharalis and D. flavipennella, 16 and 18 strains showed over 30% larval mortality in the 7th day, respectively. The LC50 values of strains for D. saccharalis varied from 0.08 × 105 (LIIT-0105) to 4104 × 105 (LIIT-2707) spores + crystals mL?1. For D. flavipennella, the LC50 values of strains varied from 0.40 × 105 (LIIT-2707) to 542 × 105 (LIIT-2109) spores + crystals mL?1. For the LIIT-0105 strain, which was the most toxic to D. saccharalis, the genes cry1Aa, cry1Ab, cry1Ac, cry1B, cry1C, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, cry8, and cry9C were detected, whereas for the strain LIIT-2707, which was the most toxic to D. flavipennella, detected genes were cry1Aa, cry1Ab, cry1Ac, cry1B, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, and cry9. The toxicity data and toxin gene content in these strains of Bt suggest a great variability of activity with potential to be used in the development of novel biopesticides or as source of resistance genes that can be expressed in plants to control pests. 相似文献
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Five new complexes [Cu2(L1)I2]∞ (1), [Cu(L2)I]2 (2), {[Cu2(L2)I2](CH3CN)3}∞ (3), [Cu2(L3)I2]∞ (4) and {[Cu(L3)I](CH3CN)}2 (5) have been obtained by reacting three structurally related ligands, 2,3-bis(n-propylthiomethyl)quinoxaline (L1), 2,3-bis(tert-butylthiomethyl)quinoxaline (L2) and 2,3-bis[(o-aminophenyl)thiomethyl]quinoxaline (L3) with CuI, respectively, at different temperatures. Single crystal X-ray analyses show that 1, 3, 4 possess 1D chain structures, while 2 and 5 are discrete dinuclear molecules. It is interesting that the reactions of CuI with L1 at room temperature and 0 °C, respectively, only afforded same structure of 1 (1a and 1b), while using L2 (or L3) instead, two different frameworks 2 and 3 (or 4 and 5) have been obtained. The structural changes mainly resulted from the different conformations that L2 or L3 adopted at different temperatures. Our research indicates that terminal groups of ligands take an essential role in the framework formation, and the reaction temperature also has important effect on the construction of such Cu(I) coordination architectures. Furthermore, the influence of hydrogen bonds on the conformation of ligands and the supramolecular structures of these complexes have also been explored. The luminescence properties of complexes 1, 2, and 4 have been studied in solid state at room temperature. 相似文献
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Tomco D Schmitt S Ksebati B Heeg MJ Dou QP Verani CN 《Journal of inorganic biochemistry》2011,105(12):1759-1766
In this paper we report on the synthesis and characterization of three cobalt complexes described as [CoII(L1)2] (1), [CoII(L2)] (2), and [CoIII(L1)2]ClO4(3). These complexes contain the deprotonated forms of the [NN′O] tridentate ligand HL1 and its newly synthesized [N2N′2O2] hexadentate counterpart H2L2, namely, 2,4-diiodo-6-((pyridine-2-ylmethylamino)methyl)phenol and 6,6′-((ethane-1,2-diylbis((pyridin-2-ylmethyl) azanediyl))bis(methylene))bis(2,4-diiodophenol). Characterizations for 1-3 include electrospray ionization (ESI) spectrometry, infrared, and UV-visible spectroscopies, and elemental analyses. A detailed 1H-NMR study was conducted for 3 and X-ray structural data was obtained for 2. The viability of this series as potential agents for proteasome inhibition and cell apoptotic induction involving PC-3 cancer cells is presented comparing the behavior of the untethered [NN′O]2 six-coordinate 1 and 3 and the tethered counterpart 2 with a 1:1 metal-to-ligand ratio. It is observed that the tethering in 2 decreases inhibition activity. When 1 and 3 are compared, the most inert, but redox-active, cobalt(III) species shows the highest chymotrypsin-like activity inhibition on purified proteasome and PC-3 cancer cells. A hypothesis based on the role of oxidation states for proteasome inhibition is offered. 相似文献
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Reactions of the β-diketiminate lithium salt L2Li [L2={(2,6-Me2C6H3)NC(Me)}2CH] with anhydrous LnCl3 (Ln=Yb, Sm, Nd) in 1:1 molar ratio in THF afforded the new β-diketiminate lanthanide complexes L2LnCl(THF)(μ-Cl)2Li(THF)2 (Ln=Yb (1), Sm (2), Nd (3)). Recrystallization of complexes 1-3 from toluene gave the neutral complexes L2LnCl2(THF)2 (Ln=Yb (4), Sm (5), Nd (6)). Recrystallization of complexes 4 and 5 in hot toluene for two times gave the dinuclear complexes L2ClLn(μ-Cl)3LnL2(THF) (Ln=Yb (7), Sm (8)). Treatment of the mother liquor of complex 2 in hot toluene for three times gave the novel trinuclear complex L2SmCl(μ-Cl)3SmL2(μ-Cl)Li(L2H)(THF) (9). Each of these complexes was well characterized, while complexes 3, 7 and 9 have been characterized by X-ray diffraction structure determination. 相似文献