Complex C3 Research Articles

Theoretical study of the interaction between 5-methylcytosine and acrylamide

The hydrogen-bonded complexes between 5-methylcytosine and acrylamide have been investigated using the density function theory (DFT) method. Five stable complexes have been found with no imaginary frequencies. Complex C3 is the most stable one with interaction energies of -69.01kJmol(-1) corrected for basis set superposition error (BSSE). The charge change in the process of these complexes formation has also been examined. The atoms in molecules (AIM) theory and natural bond orbital (NBO) method have been performed to investigate the hydrogen bonds involved in all the complexes. The electron density and its corresponding Laplacian at the bond and ring critical points have been analyzed. In C3 complex, there is the largest stabilization energy (18.17kJmol(-1)) between N11-H12 antibonding orbital and lone electron pair of O17. It can be seen that the hydrogen bonds play a crucial role in the stability of all the complexes between 5-methylcytosine and acrylamide. The theoretical results could provide helpful information for other researchers in further work.

New Heteroleptic Bis-Phenanthroline Copper(I) Complexes with Dipyridophenazine or Imidazole Fused Phenanthroline Ligands: Spectral, Electrochemical, and Quantum Chemical Studies

Two new sterically challenged diimine ligands L(1) (2,9-dimesityl-2-(4'-bromophenyl)imidazo[4,5-f][1,10]phenanthroline) and L(2) (3,6-di-n-butyl-11-bromodipyrido[3,2-a:2',3'-c]phenazine) have been synthesized with the aim to build original heteroleptic copper(I) complexes, following the HETPHEN concept developed by Schmittel and co-workers. The structure of L(1) is based on a phen-imidazole molecular core, derivatized by two highly bulky mesityl groups in positions 2 and 9 of the phenanthroline cavity, preventing the formation of a homoleptic species, while L(2) is a dppz derivative, bearing n-butyl chains in α positions of the chelating nitrogen atoms. The unambiguous formation of six novel heteroleptic copper(I) complexes based on L(1), L(2), and complementary matching ligands (2,9-R(2)-1,10-phenanthroline, with R = H, methyl, n-butyl or mesityl) has been evidenced, and the resulting compounds were fully characterized. The electronic absorption spectra of all complexes fits well with DFT calculations allowing the assignment of the main transitions. The characteristics of the emissive excited state were investigated in different solvents using time-resolved single photon counting and transient absorption spectroscopy. The complexes with ligand L(2), bearing a characteristic dppz moiety, exhibit a very low energy excited-state which mainly leads to fast nonradiative relaxation, whereas the emission lifetime is higher for those containing the bulky ligand L(1). For example, a luminescence quantum yield of about 3 × 10(-4) is obtained with a decay time of about 50 ns for C2 ([Cu(I)(nBu-phen)(L(1))](+)) with a weak influence of strong coordinating solvent on the luminescence properties. Overall, the spectral features are those expected for a highly constrained coordination cage. Yet, the complexes are stable in solution, partly due to the beneficial π stacking between mesityl groups and vicinal phenanthroline aromatic rings, as evidenced by the X-ray structure of complex C3 ([Cu(I)(Mes-phen)(L(2))](+)). Electrochemistry of the copper(I) complexes revealed reversible anodic behavior, corresponding to a copper(I) to copper(II) transition. The half wave potentials increase with the steric bulk at the level of the copper(I) ion, reaching a value as high as 1 V vs SCE, with the assistance of ligand induced electronic effects. L(1) and L(2) are further end-capped by a bromo functionality. A Suzuki cross-coupling reaction was directly performed on the complexes, in spite of the handicapping lability of copper(I)-phenanthroline complexes.

Die Ellenbogentotalendoprothese in der Versorgung schwerer Ellenbogenverletzungen des älteren Patienten

The aim of this study was to evaluate the functional outcome of patients with severe elbow injuries treated by primary and secondary implantation of an elbow prosthesis using two different functional scores. To determine whether or not total elbow replacement is an acceptable treatment option in such cases, we analysed the functional outcome of patients after primary or secondary implantation of the semi-constrained Coonrad-Morrey prosthesis. Between March 2005 and September 2009 we implanted 25 Coonrad-Morrey prostheses in 24 patients with acute or chronic elbow injuries. Eight patients had complex type C3 fractures according to the AO classification and were treated with primary implantation. 16 patients received a secondary implantation including 3 chronic luxations, 3 non-unions of the bone, 3 failed osteosyntheses, 7 patients with post-traumatic arthrosis and 1 reimplantation. The mean follow-up after the operation was 12 (± 8) months. The functional outcome was measured by assembling the "Mayo elbow prosthesis score" and the "Mayo elbow performance score". We had 15 female and 9 male patients with a mean age of 67 (± 6) years. All 24 patients achieved very good results based on the used scores with a mean of 97 points each with a maximum performance of 100 points. The mean range of motion concerning extension and flexion was 92 degrees (range 55 to 115 degrees), concerning pronation and supination 144 degrees (range 100 to 160 degrees). The mean flexion deformity was 19 degrees (range 10 to 50 degrees), the mean maximum flexion was 112 degrees (range 90 to 130 degrees). During the follow-up we had two partial ruptures of the triceps tendon, one temporary lesion of the ulnar nerve with complete recovery after surgical revision and one postoperative haematoma which needed surgical treatment. One patient needed revision surgery and resection arthroplasty due to a deep infection, but received a new prosthesis after two months. We recorded no radiographic loosening or other mechanical problems. Due to the good functional outcome and pain relief of patients treated by total elbow replacement, we suggest that total elbow arthroplasty is a reasonable treatment option for complex acute and chronic injuries of the elbow in elderly patients.

Synthesis, characterization and ethylene oligomerization behavior of 2-(chloro-substituted-1 H-benzoimidazol-2-yl)-6-(1-aryliminoethyl)pyridylnickel dihalides

A series of 2-(chloro-substituted-1 H-benzoimidazol-2-yl)-6-(1-aryliminoethyl)pyridines ( L1– L6) was synthesized and fully characterized. They reacted with NiCl 2 or (DME)NiBr 2 to form the corresponding N^N^N tridentate nickel dichlorides ( C1– C6) or dibromides ( C7– C12). All nickel complexes were characterized by elemental analysis and infrared spectroscopy, while the X-ray diffraction study reveals the distorted octahedral geometry of representative nickel dichloride complex C3 and nickel dibromide complex C7. All nickel complexes, activated with either Et 3Al 2Cl 3 or Et 2AlCl, showed good activities in ethylene oligomerization, and notably remarkably high selectivity of α-olefins was achieved in the presence of Et 3Al 2Cl 3. The chloro-substituted ligands enhanced the activities of complexes in ethylene polymerization.

Synthesis and properties of new Mo(II) complexes with N-heterocyclic and ferrocenyl ligands

New Mo(II) complexes with 2,2′-dipyridylamine ( L1), [Mo(CH 3CN)(η 3-C 3H 5)(CO) 2(L1)]OTf ( C1a) and [{MoBr(η 3-C 3H 5)(CO) 2(L1)} 2(4,4′-bipy)](PF 6) 2 ( C1b), with {[bis(2-pyridyl)amino]carbonyl}ferrocene ( L2), [MoBr(η 3-C 3H 5)(CO) 2(L2)] ( C2), and with the new ligand N, N-bis(ferrocenecarbonyl)-2-aminopyridine ( L3), [MoBr(η 3-C 3H 5)(CO) 2(L3)] ( C3), were prepared and characterized by FTIR and 1H and 13C NMR spectroscopy. C1a, C1b, L3, and C2 were also structurally characterized by single crystal X-ray diffraction. The Mo(II) coordination sphere in all complexes features the facial arrangement of allyl and carbonyl ligands, with the axial isomer present in C1a and C2, and the equatorial in the binuclear C1b. In both C1a and C1b complexes, the L1 ligand is bonded to Mo(II) through the nitrogen atoms and the NH group is involved in hydrogen bonds. The X-ray single crystal structure of C2 shows that L2 is coordinated in a κ 2-N,N-bidentate chelating fashion. Complex C3 was characterized as [MoBr(η 3-C 3H 5)(CO) 2(L3)] with L3 acting as a κ 2-N,O-bidentate ligand, based on the spectroscopic data, complemented by DFT calculations. The electrochemical behavior of the monoferrocenyl and diferrocenyl ligands L2 and L3 has been studied together with that of their Mo(II) complexes C2 and C3. As much as possible, the nature of the different redox changes has been confirmed by spectrophotometric measurements. The nature of the frontier orbitals, namely the localization of the HOMO in Mo for both in C2 and C3, was determined by DFT studies.

Synthesis, Characterization, and Ethylene Oligomerization and Polymerization by 2-Quinoxalinyl-6-iminopyridine Chromium Chlorides

A series of chromium(iii) complexes ligated by N^N^N tridentate 2-quinoxalinyl-6-iminopyridine were synthesized and characterized by elemental analysis and infrared spectroscopy. Single-crystal X-ray diffraction analysis for the structure of complex C3 reveals a distorted octahedral geometry. When methylaluminoxane was employed as the co-catalyst, the chromium complexes showed high activities for ethylene oligomerization and polymerization. The distribution of oligomers obtained followed Schulz–Flory rules with high selectivity for α-olefins. Both steric and electronic effects of coordinated ligands affected the catalytic activities as well as the properties of the catalytic products. The parameters of the reaction conditions were also investigated to explore the optimum catalytic potentials of these complexes.

In vitro Antimicrobial and Cytotoxic Activities of Ferrocene Derivative Compounds

The aim of the present study was to investigate the biocidal activity of four new ferrocene derivative based coordination complexes, [1,2,3-trithia-/3/-ferrocenophane, C1]; [disodium-1,1'-ferrocenedithiolate, C2]; [1,1'-(ferrocene-1,1'-diyl)-diethanol, C3]; [ferrocenyl(ethyl-phenyl)-methanol, C4]; against microbes (bacteria and fungi) and brine shrimp (Artemia salina Lech.) nauplii. C2 showed modest antibacterial activity at the concentration of 200 microg disc(-1) and gave its Minimum Inhibitory Concentration values at 32-64 microg mL(-1) against the tested bacteria. These complexes gave comparatively better antibacterial activity against the Gram-positives than the Gram-negatives. C3, C1 and C4 showed moderate antifungal activity at concentration of 200 microg disc(-1). Brine shrimp eggs were hatched in artificial sea water and exposed to the complexes. Median lethal concentration (LC50) values were calculated. Both complexes showed toxicity against brine shrimp but complex C3 explored its potent cytotoxicity having LC50 values at 6.031 microg mL(-1) (ppm).

DAF/Crry double deficiency in mice exacerbates nephrotoxic serum-induced proteinuria despite markedly reduced systemic complement activity

Decay-accelerating factor (DAF) and complement receptor 1-related gene/protein y (Crry) are two membrane-anchored complement regulatory proteins in rodent. Although both proteins are broadly distributed and exert complement regulation at the same steps of the complement cascade, DAF knockout mice are viable whereas Crry knockout mice die in utero as a result of maternal complement attack. The latter outcome has prevented the dissection of overlapping functions of DAF and Crry in adult mouse tissues in vivo. By crossing female DAF −/−/Crry −/−/C3 −/− mice with male DAF −/−/Crry +/−/C3 +/− mice, we circumvented maternal complement attack during fetal development and generated viable DAF −/−/Crry −/−/C3 +/− mice to address the consequence of DAF/Crry double deficiency. DAF −/−/Crry −/−/C3 +/− mice were born at the expected frequency and survived to adulthood. However, they were found to have greatly reduced systemic complement activity due, at least in part, to spontaneous C3 activation and consumption. Plasma C3 proteins in DAF −/−/Crry −/−/C3 +/− mice were 30% of that of wild-type mice, and serum complement activity, as assessed by zymosan and immune complex C3 opsonization assays, was 90% reduced in DAF −/−/Crry −/−/C3 +/− mice. Remarkably, despite greatly reduced systemic complement activity, DAF −/−/Crry −/−/C3 +/− mice developed more severe proteinuria after induction of nephrotoxic serum nephritis as compared with DAF −/−/Crry +/−/C3 +/− and DAF −/−/Crry −/−/C3 −/− littermate controls. The results highlight the critical and overlapping role of Crry and DAF in vivo in preventing complement activation and tissue injury.

A Trypanosoma brucei Protein Complex That Binds G-overhangs and Co-purifies with Telomerase Activity

The chromosomal ends of Trypanosoma brucei, like those of most eukaryotes, contain conserved 5'-TTAGGG-3' repeated sequences and are maintained by the action of telomerase. Fractionated T. brucei cell extracts with telomerase activity were used as a source of potential regulatory factors or telomerase-associated components that might interact with T. brucei telomeres. Electrophoretic mobility shift assays and UV cross-linking were used to detect possible single-stranded telomeric protein.DNA complexes and to estimate the approximate size of the protein constituents. Three single-stranded telomeric protein.DNA complexes were observed. Complex C3 was highly specific for the G-strand telomeric repeat sequence and shares biochemical characteristics with G-rich, single-stranded telomeric binding proteins and with components of the telomerase holoenzyme described in yeast, ciliates, and humans. Susceptibility to RNase A or chemical nuclease (hydroxyl radical) pre-treatment showed that complex C3 was tightly associated with an RNA component. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry was used to estimate the molecular mass of the peptides obtained by in-gel Lys-C digestion of low abundance C3-associated proteins. The molecular masses of the peptides showed no homologies with other proteins from trypanosomes or with any protein in the data bases screened.

Kinetic mechanism for the model reaction of NADPH-cytochrome P450 oxidoreductase with cytochrome c.

The kinetic mechanism of NADPH-cytochrome P450 oxidoreductase (P450R) has been determined for the model reaction with cytochrome c3+. Although initial velocity studies show parallel patterns, consistent with a classical (one-site) ping-pong mechanism that precludes the formation of a ternary NADPH-P450R-cytochrome c3+ complex, product and dead-end inhibition results suggest a nonclassical (two-site) ping-pong mechanism [Northrop, D. B. (1969) J. Biol. Chem. 244, 5808-5819]. This mechanism is a hybrid of the random sequential (ternary complex) and ping-pong mechanisms, since ternary complexes can form as well as intermediate, modified forms of the enzyme that can be present in the absence of any bound substrate. The complete rate equation is derived for this mechanism, and values for Vmax, (V/K)NADPH, (V/K)cytc, and the corresponding Michaelis constants are presented in terms of microscopic rate constants along with the expected product inhibition patterns (Appendix). Inhibition by NADP+ is competitive versus NADPH and uncompetitive versus cytochrome c3+, while inhibition by cytochrome c2+ is competitive versus cytochrome c3+ and noncompetitive versus NADPH. These inhibition patterns are consistent with the proposed two-site mechanism. This mechanism would give the same initial velocity patterns as the classical one-site ping-pong mechanism, but it allows for the formation of a ternary complex, with NADPH and cytochrome c3+ reacting independently at two separate sites on P450R. The D(V/K)NADPH isotope effect is not affected by cytochrome c3+ concentration, consistent with our assumption (in deriving the rate equation) that binding at the two sites is independent. At the high ionic strength used in this study (850 mM), the mechanism is two-site ping-pong, with the electron acceptor site itself reacting with cytochrome c3+ in a tetra uni ping-pong manner.

Nucleation, growth, and morphology of dust in plasmas

Abstract

Realizations of generators of complex angular momentum

We use the generators of complex angular momentum in complex c3 space and derive the realizations of the homogeneous Lorentz group for nonzero real mass, zero mass, and imaginary mass systems. We use the appropriate little group for different systems to calculate the modifications in the spin contribution to angular momentum and the unphysical continuous spin representations are shown to be eliminated. We diagonalize the helicity operator in c3 space and obtain the generators of complex angular-momentum operators, which are shown to lead, in a general manner, to the standard helicity representations of the Poincare group for timelike and spacelike systems.

Schistosoma japonicum: Semiquantitative assessment of circulating immune complexes, serum Clq and C3, and their relationship to renal pathology and hepatic fibrosis in rabbits

Ten New Zealand white rabbits were infected either once or four times with variable numbers of Schistosoma japonicum cercariae. Four animals served as the uninfected controls. All rabbits were bled at semimonthly intervals. Serum samples were examined for circulating immune complexes using an [ 125I]Clq assay, or for Clq and C3 levels by single radial immunodiffusion. Control and experimental animals were necropsied at 32–39 weeks postinfection, and the kidneys and livers were removed. Some kidney specimens were quick-frozen in isopentane-liquid nitrogen, cut with a cryostat, and examined by direct or indirect immunofluorescent techniques for immunoglobulin, complement (C3), or parasite antigen glomerular localization. Other kidney specimens were fixed in formalin, sectioned, stained with H&E or PAS, and examined for evidence of histopathology. Liver specimens were treated in a similar manner. Diffuse renal lesions appeared in only 2 of 10 rabbits in the present study. However, each of these two animals had prominent and persistent levels of circulating [ 125I]Clq material (immune complex), and the animal with the highest concentration of immune complex had the most severe nephropathologic changes. C3 levels were consistently depressed in the animal with severe renal pathology but were elevated in all other animals at some point in the infection. Circulating immune complex and serum C3 and Clq values moved in concert for most of the infected rabbits with the principal exception being the animals with diffuse renal lesions. It is of considerable interest and potential etiological significance that the four rabbits with the highest levels of circulating immune complex had the most extensive hepatic fibrosis.