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Nuclear Magnetic Resonance Spectrum of Lysine-Vasopressin in Aqueous Solution and Its Structural Implications

Dreele, P. H. Von; Brewster, A. I.; Dadok, J.; Scheraga, H. A.; Bovey, F. A.; Ferger, M. F.; Vigneaud, V. Du
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1972 EN
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The peaks in the proton NMR spectrum of lysine-vasopressin in aqueous solution at pH 3-5 were assigned to particular amino-acid residues by the use of the results of dilution studies and NH-CαH and CαH-CβH decoupling experiments. The conformation of lysine-vasopressin in water differs from its conformation in dimethylsulfoxide.

Tautomerism of Uracil and Thymine in Aqueous Solution: Spectroscopic Evidence

Daniels, Malcolm
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1972 EN
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Excitation spectra for triplet state formation and fluorescence emission from uracil and thymine in neutral aqueous solution at room temperature are anomalous when compared to the absorption spectra of uracil and thymine.

300-MHz Nuclear Magnetic Resonance Study of Oxytocin in Aqueous Solution: Conformational Implications

Brewster, A. I. Richard; Hruby, V. J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1973 EN
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The 300-MHz nuclear magnetic resonance spectrum of the peptide hormone, oxytocin, in water, was obtained. Extensive nuclear magnetic resonance spindecoupling experiments, including those involving irradiation of the α-proton resonance under the water peak, studies using partially deuterated hormone derivatives, and nuclear magnetic resonance studies of some precursor peptides to oxytocin, permitted us to assign most of the proton resonance of the hormone unambiguously. The JNα values and temperature dependence of the chemical shift of the peptide amide and carboxamide protons of oxytocin were also obtained. These studies indicate that, in aqueous solution, oxytocin is a flexible molecule possessing several different conformations. Corresponding studies of [4-leucine]oxytocin were also made, with similar results and conclusions.

Coherent anti-Stokes Raman scattering (CARS) spectra, with resonance enhancement, of cytochrome c and vitamin B12 in dilute aqueous solution.

Nestor, J; Spiro, T G; Klauminzer, G
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1976 EN
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Coherent anti-Stokes Raman scattering (CARS) spectra have been obtained for ferrocytochrome c and cyano cobalamin in aqueous solution at millimolar concentrations, using a pair of tunable dye lasers pumped by a pulsed nitrogen laser. Resonance enhancement was obtained by tuning the omega1 laser to the visible absorption bands of the samples. The spectral features correspond to those observed in the conventional resonance Raman spectra. It appears that CARS spectroscopy, with its advantageous fluorescence rejection, can be usefully applied to biological samples by exploiting resonance enhancement. While the background scattering from water is 10 times higher than that of benzene and other aromatic solvents, it is actually at the low end of the scale for most liquids. The anomalously low background of aromatic liquids is thought to result from competition by the unusually efficient stimulated Raman scattering which they display. Off-resonance spectra for both cobalamin and cytochrome c contain negative peaks, i.e., absorption bands in the background. These are interpreted as inverse Raman processes induced by the omega1 photons in the presence of the continuum provided by the background scattering. While both CARS and the inverse Raman effect are subject to resonance enhancement...

Kinetic Studies of the Thermal Decomposition of 2-Chloroethylphosphonic Acid in Aqueous Solution

Biddle, Eric; Kerfoot, Douglas G. S.; Kho, Yioe Hwa; Russell, Kenneth E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1976 EN
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The decomposition of 2-chloroethylphosphonic acid in aqueous solution has been studied at pH values from 6 to 9 and at temperatures in the 30 to 55 C range. The rate of decomposition is estimated from the rate of formation of ethylene. The rate is proportional to the concentration of the phosphonate dianion and is independent of the hydroxyl ion concentration. The rate constant at 40 C is 1.9 × 10−4 sec−1 and the activation energy is 29.8 kcal mol−1. The rate of reaction is not affected significantly by the presence of potassium iodide or urea (substances which increase the rate of leaf abscission in trees sprayed by 2-chloroethylphosphonic acid). The rate decreases slightly in the presence of low concentrations of magnesium and calcium ions.

Metal ion-binding properties of (N3)-deprotonated uridine, thymidine, and related pyrimidine nucleosides in aqueous solution

Knobloch, Bernd; Linert, Wolfgang; Sigel, Helmut
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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The acidity constants for (N3)H of the uridine-type ligands (U) 5-fluorouridine, 5-chloro-2′-deoxyuridine, uridine, and thymidine (2′-deoxy-5-methyluridine) and the stability constants of the M(U–H)+ complexes for M2+ = Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ were measured (potentiometric pH titrations; aqueous solution; 25°C; I = 0.1 M, NaNO3). Plots of documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} setlength{oddsidemargin}{-69pt} egin{document} egin{equation*}{mathrm{log}}K_{{mathrm{M}}({mathrm{U}}-{mathrm{H}})}^{{mathrm{M}}}end{equation*}end{document} vs. documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} setlength{oddsidemargin}{-69pt} egin{document} egin{equation*}{mathrm{p}}K_{{mathrm{U}}}^{{mathrm{H}}}end{equation*}end{document} result in straight lines that are compared with previous plots for simple pyridine-type and o-amino(methyl)pyridine-type ligands as well as with the stabilities of the corresponding M(cytidine)2+ complexes. The results indicate monodentate coordination to (N3)– in M(U–H)+ for Co2+ and Ni2+. For the M(U–H)+ species of Cd2+...

An extended-X-ray-absorption-fine-structure study of bovine erythrocyte superoxide dismutase in aqueous solution. Direct evidence for three-co-ordinate Cu(I) in reduced enzyme.

Blackburn, N J; Hasnain, S S; Binsted, N; Diakun, G P; Garner, C D; Knowles, P F
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/05/1984 EN
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Copper and zinc K-edge e.x.a.f.s. (extended X-ray-absorption fine structures) were measured for the metal sites of oxidized and reduced bovine superoxide dismutase in aqueous solution. Detailed analysis of the spectra indicates that the copper site of the enzyme changes on reduction and is most probably co-ordinated to three imidazole groups at a shorter distance Cu-N(alpha) = 0.194 nm (1.94 A) in the reduced form compared with a co-ordination of four imidazole groups at 0.199 nm (1.99 A) and an oxygen atom from solvent water at 0.224 nm (2.24 A) in the oxidized form. Examination of the edge, near-edge structure and e.x.a.f.s. of the zinc sites indicates that the stereochemical changes at copper that accompany reduction introduce minimal perturbation on the stereochemistry at zinc.

Equilibrium and kinetic studies of the aggregation of porphyrins in aqueous solution.

Brown, S B; Shillcock, M; Jones, P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/02/1976 EN
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An investigation of the behavior of protoporphyrin IX, deuteroporphyrin IX, haematoporphyrin IX and coproporphyrin III in aqueous solution revealed extensive and complex aggregation processes. Protoporphyrin appears to be highly aggregated under all conditions studied. At concentrations below 4 muM, aggregation of deutero-, haemato- and coproporphyrin is probably restricted to dimerization. At approx. 4muM each of these three porphyrins exhibits sharp changes in spectra consistent with a "micellization" process to form large aggregates of unknown size. This critical concentration increases with increasing temperature and pH, but is not very sensitive to variation in ionic strength. Temperature-jump kinetic studies on deuteroporphyrin also imply an initial dimerization process, the rate constants for which are comparable with those for various synthetic porphyrins, followed by a further extensive aggragation. The ability of a particular porphyrin to dimerize appears to parallel that of the corresponding iron(III) complexes (ferrihaems), although it is thought that ferrihaems do not exhibit further aggregation under these conditions.

The effect of chondromucoprotein on the solubility and peroxidatic properties of haemoglobin and methaemalbumin in aqueous solution and blood

Anderson, A. J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1965 EN
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1. Insoluble complexes, formed by electrostatic interaction between chondromucoprotein and chromoproteins (haemoglobin, methaemalbumin), were studied by measurement of precipitated pigment and by decrease in peroxidatic activity, maximum formation from aqueous solution occurring at pH 4·0–4·6. 2. Chondromucoprotein did not form complexes with plasma haptoglobins and haptohaemoglobins under these conditions, and high concentrations had no significant effect on colorimetric estimates of serum haptoglobin, although the peroxidatic activity of haemoglobinaemic serum was depressed owing to formation of chondromucoprotein–methaemalbumin complex. 3. The complexes formed by interaction between chondromucoprotein and plasma proteins contain two protein-bound biologically active components (plasminogen, haematin), as a result of co-precipitation after interaction between their carriers and chondromucoprotein. The possible presence of other biologically active trace components is discussed. 4. The results are related to complex-formation between other plasma proteins and chondromucoprotein, and possible implications arising from the complex-forming properties of tissue and urine chondromucoprotein are referred to. It is concluded that the inability of chondromucoprotein to form complexes with normal urine proteins is due to a deficiency of fibrinogen...

Formation of an active dimer during storage of interleukin-1 receptor antagonist in aqueous solution.

Chang, B S; Beauvais, R M; Arakawa, T; Narhi, L O; Dong, A; Aparisio, D I; Carpenter, J F
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1996 EN
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The degradation products of recombinant human interleukin-1 receptor antagonist (rhIL-1ra) formed during storage at 30 degrees C in aqueous solution were characterized. Cationic exchange chromatography of the stored sample showed two major, new peaks eluting before (P1) and after (L2) the native protein, which were interconvertible. Size-exclusion chromatography and electrophoresis documented that both the P1 and L2 fractions were irreversible dimers, formed by noncovalent interactions. A competition assay with interleukin-1 indicated that on a per monomer basis the P1 and L2 dimers retained about two-thirds of the activity of the native monomer. Infrared and far-UV circular dichroism spectroscopies showed that only minor alterations in secondary structure arose upon the formation of the P1 dimer. However, alteration in the near-UV circular dichroism spectrum suggested the presence of disulfide bonds in the P1 dimer, which are absent in the native protein. Mass spectroscopy and tryptic mapping, before and after carboxymethylation, demonstrated that the P1 dimer contained an intramolecular disulfide bond between Cys-66 and Cys-69. Although conversion of native protein to the P1 dimer was irreversible in buffer alone, the native monomer could be regained by denaturing the P1 dimer with guanidine hydrochloride and renaturing it by dialysis...

Filipin fluorescence quenching by spin-labeled probes: studies in aqueous solution and in a membrane model system.

Castanho, M; Prieto, M
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1995 EN
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A detailed photophysical study of the fluorescence quenching (transient and steady state) of the macrolide antibiotic filipin by nitroxide-substituted fatty acids and a cholesterol derivative was carried out, aimed at determining its transverse position in a model system of membranes (multilamellar vesicles of dipalmitoylphosphatidylcholine). Filipin partitions efficiently into membranes (Kp = (5.0 +/- 1.0).10(3), 20 degrees C) and it was concluded that the antibiotic is buried in the membrane, away from the lipid-water interface. In addition, information on the organization of the quenchers was also obtained. The 5-nitroxide derivative of the fatty acid is essentially randomly distributed, while the 16-nitroxide is aggregated at concentrations higher than approximately 5% molar. For the cholesterol compound the results point to a phase separation at concentrations higher than 3% molar (below this limit concentration filipin associates with the derivatized sterol with KA = 20 M-1, assuming a 1:1 interaction). We propose that this phase separation and the aggregation state of filipin in the aqueous solution may be key processes in the antibiotic mode of action. A systematic and general approach to fluorescence quenching data analysis in complex (e.g....

A free energy analysis of nucleic acid base stacking in aqueous solution.

Friedman, R A; Honig, B
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1995 EN
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This paper reports a theoretical study of the free energy contributions to nucleic acid base stacking in aqueous solution. Electrostatic interactions are treated by using the finite difference Poisson-Boltzmann method and nonpolar effects are treated with explicit calculation of van der Waals interactions and/or free energy-surface area relationships. Although for some pairs of bases there is a favorable Coulombic interaction in the stacked conformation, generally the net effect of electrostatic interactions is to oppose stacking. This result is caused by the loss of favorable base-solvent electrostatic interactions, that accompany the partial removal of polar atoms from water in the stacked conformation. Nonpolar interactions, involving the hydrophobic effect and enhancement of van der Waals interactions caused by close-packing, drive stacking. The calculations qualitatively reproduce the experimental dependence of stacking free energy on purine-pyrimidine composition.

Molecular dynamics studies of the interface between a model membrane and an aqueous solution.

Nicklas, K; Böcker, J; Schlenkrich, M; Brickmann, J; Bopp, P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1991 EN
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Molecular Dynamics (MD) computer simulation studies are reported for a system consisting of two model membranes in contact with an aqueous solution. The influence of the membrane on the adjacent liquid is of main interest in the present study. It is therefore attempted to make the system sufficiently large to encompass the entire region between bulk liquid and the membranes. The latter are modeled by two-dimensional arrays of COO- groups with rotational and translational degrees of freedom. The water molecules are represented by the well-tested TIP4P model. The intermolecular potentials are parametrized in terms of Coulomb interactions between partial charges on the molecular frames and empirical, mostly Lennard-Jones (12-6), interactions centered at the atomic positions. A strong layering of the liquid accompanied by an increase in average water density is found in the vicinity of the membrane. The structural perturbation reaches approximately 8 A into the liquid. We discuss the static structure in these layers in terms of atom-atom distance distribution functions and study the average orientation of the water molecule dipoles with respect to the membrane. From the distribution of the ions, we find that less than 50% of the surface charge of the membrane is neutralized by Na+ ions in the first layer above the membrane. A simplified model of the adsorption site of the ion on the membrane is developed from the distance distributions. Finally the hydration of the Na+ in the first adsorbed layer is discussed.

Rod-like cholesterol micelles in aqueous solution studied using polarized and depolarized dynamic light scattering.

Castanho, M A; Brown, W; Prieto, M J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1992 EN
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Micelles of cholesterol in aqueous solution have been investigated using polarized and depolarized dynamic light scattering. They are shown to be highly extended and characterized by a narrow size distribution. It is shown that a rod-like model is applicable with length, L = 580 nm. Determination of the rotational diffusion coefficient by analysis of the autocorrelation function gave a value of theta = 150 s-1, which is close to the calculated value for the rod with this dimension. Depolarized dynamic light scattering measurements as a function of angle gave a value of 110 s-1.

Small Angle X-Ray Scattering Study of Meso-Tetrakis (4-Sulfonatophenyl) Porphyrin in Aqueous Solution: A Self-Aggregation Model

Gandini, S.C.M.; Gelamo, E.L.; Itri, R.; Tabak, M.
Fonte: Biophysical Society Publicador: Biophysical Society
Tipo: Artigo de Revista Científica
Publicado em /08/2003 EN
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The aggregate morphology of meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS4) in aqueous solution is investigated by using small angle x-ray scattering (SAXS) technique. Measurements were performed at pH 4.0 and 9.0 to monitor the pH influence on the structural parameters of the aggregates. Radii of gyration were obtained from distance distribution functions p(r) analysis. The experimental data of TPPS4 at pH 4.0 showed well-defined oscillations characteristic of large aggregates in contrast to the SAXS curve of 5 mM TPPS4 at pH 9.0, where both a significant decrease in the intensity and the disappearance of the oscillation peaks suggest the dissociation of the aggregate. A 340-Å long “hollow” cylinder with shell thickness of 20 Å, compatible to the porphyrin molecule dimension, represents well the scattering curve of the aggregates at pH 4.0. According to the fitting parameters, 26 porphyrin molecules self-associate into a ringlike configuration in the plane of the cylinder cross-section. The total number of porphyrin molecules in the whole aggregate was also estimated as ∼3000. The model compatible to SAXS data of a hollow cylinder with J-aggregation in the cross-section and H-aggregation (columnar stacking) between the cylinder layers is consistent with optical absorption spectroscopic data both in the literature and obtained in this work.

A Raman spectroscopic study of arsenite and thioarsenite species in aqueous solution at 25°C

Wood, Scott A; Tait, C Drew; Janecky, David R
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em 26/02/2002 EN
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The Raman spectra of thioarsenite and arsenite species in aqueous solution were obtained at room temperature. Solutions at constant ΣAs + ΣS of 0.1 and 0.5 mol kg-1 were prepared with various ΣS/ΣAs ratios (0.1–9.0) and pH values (~7–13.2). Our data suggest that the speciation of As under the conditions investigated is more complicated than previously thought. The Raman measurements offer evidence for at least six separate S-bearing As species whose principal bands are centered near 365, 385, 390, 400, 415 and 420 cm-1. The data suggest that at least two different species may give rise to bands at 385 cm-1, bringing the probable minimum number of species to seven. Several additional species are possible but could not be resolved definitively. In general, the relative proportions of these species are dependent on total As concentration, ΣS/ΣAs ratio and pH. At very low ΣS/ΣAs ratios we also observe Raman bands attributable to the dissociation products of H3AsO3(aq). Although we were unable to assign precise stoichiometries for the various thioarsenite species, we were able to map out general pH and ΣS/ΣAs conditions under which the various thioarsenite and arsenite species are predominant. This study provides a basis for more detailed Raman spectroscopic and other types of investigations of the nature of thioarsenite species.

Internal conversion to the electronic ground state occurs via two distinct pathways for pyrimidine bases in aqueous solution

Hare, Patrick M.; Crespo-Hernández, Carlos E.; Kohler, Bern
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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The femtosecond transient absorption technique was used to study the relaxation of excited electronic states created by absorption of 267-nm light in all of the naturally occurring pyrimidine DNA and RNA bases in aqueous solution. The results reveal a surprising bifurcation of the initial excited-state population in <1 ps to two nonradiative decay channels within the manifold of singlet states. The first is the subpicosecond internal conversion channel first characterized in 2000. The second channel involves passage through a dark intermediate state assigned to a lowest-energy 1nπ* state. Approximately 10–50% of all photoexcited pyrimidine bases decay via the 1nπ* state, which has a lifetime of 10–150 ps. Three- to 6-fold-longer lifetimes are seen for pyrimidine nucleotides and nucleosides than for the corresponding free bases, revealing an unprecedented effect of ribosyl substitution on electronic energy relaxation. A small fraction of the 1nπ* population is proposed to undergo intersystem crossing to the lowest triplet state in competition with vibrational cooling, explaining the higher triplet yields observed for pyrimidine versus purine bases at room temperature. Some simple correlations exist between yields of the 1nπ* state and yields of some pyrimidine photoproducts...

Electron attachment to DNA single strands: gas phase and aqueous solution

Gu, Jiande; Xie, Yaoming; Schaefer, Henry F.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
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The 2′-deoxyguanosine-3′,5′-diphosphate, 2′-deoxyadenosine-3′,5′-diphosphate, 2′-deoxycytidine-3′,5′-diphosphate and 2′-deoxythymidine-3′,5′-diphosphate systems are the smallest units of a DNA single strand. Exploring these comprehensive subunits with reliable density functional methods enables one to approach reasonable predictions of the properties of DNA single strands. With these models, DNA single strands are found to have a strong tendency to capture low-energy electrons. The vertical attachment energies (VEAs) predicted for 3′,5′-dTDP (0.17 eV) and 3′,5′-dGDP (0.14 eV) indicate that both the thymine-rich and the guanine-rich DNA single strands have the ability to capture electrons. The adiabatic electron affinities (AEAs) of the nucleotides considered here range from 0.22 to 0.52 eV and follow the order 3′,5′-dTDP > 3′,5′-dCDP > 3′,5′-dGDP > 3′,5′-dADP. A substantial increase in the AEA is observed compared to that of the corresponding nucleic acid bases and the corresponding nucleosides. Furthermore, aqueous solution simulations dramatically increase the electron attracting properties of the DNA single strands. The present investigation illustrates that in the gas phase, the excess electron is situated both on the nucleobase and on the phosphate moiety for DNA single strands. However...

Metal Ion-Binding Properties of the Diphosphate Ester Analogue, Methylphosphonylphosphate, in Aqueous Solution

Song, Bin; Zhao, Jing; Gregáň, Fridrich; Prónayová, Nadja; Sajadi, S. Ali A.; Sigel, Helmut
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em //1999 EN
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The stability constants of the 1:1 complexes formed between methylphosphonylphosphate (MePP3-), CH3P(O)-2-O-PO32-, and Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, ​ or Cd2+ (M2+) were determined by potentiometric pH titration in aqueous solution (25 °C; l = 0.1 M, NaNO3). Monoprotonated M(H;MePP) complexes play only a minor role. Based on previously established correlations for M2+-diphosphate monoester complex-stabilities and diphosphate monoester β-group. basicities, it is shown that the M(Mepp)- complexes for Mg2+ and the ions of the second half of the 3d series, including Zn2+ and Cd2+, are on average by about 0.15 log unit more stable than is expected based on the basicity of the terminal phosphate group in MePP3-. In contrast, Ba(Mepp)- and Sr(Mepp)- are slightly less stable, whereas the stability for Ca(Mepp)- is as expected, based on the mentioned correlation. The indicated increased stabilities are explained by an increased basicity of the phosphonyl group compared to that of a phosphoryl one. For the complexes of the alkaline earth ions, especially for Ba2+, it is suggested that outersphere complexation occurs to some extent. However, overall the M(Mepp)- complexes behave rather as expected for a diphosphate monoester ligand.

Rapid Crosslinking of Elastin-like Polypeptides with Hydroxymethylphosphines in Aqueous Solution

Lim, Dong Woo; Nettles, Dana L.; Setton, Lori A.; Chilkoti, Ashutosh
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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In-situ gelation of injectable polypeptide-based materials is attractive for minimally invasive in vivo implantation of biomaterials and tissue engineering scaffolds. We demonstrate that chemically crosslinked elastin-like polypeptide (ELP) hydrogels can be rapidly formed in aqueous solution by reacting lysine containing ELPs with an organophosphorous crosslinker, β-[tris(hydroxymethyl)phosphino]-propionic acid (THPP) under physiological conditions. The mechanical properties of the crosslinked ELP hydrogels were largely modulated by the molar concentration of lysine residues in the ELP and the pH at which the crosslinking reaction was carried out. Fibroblasts embedded in ELP hydrogels survived the crosslinking process and were viable after in vitro culture for 3 days. DNA quantification of ELP hydrogels with encapsulated fibroblasts indicated that there was no significant difference in DNA content between day 0 and day 3 when ELP hydrogels were formed with an equimolar ratio of THPP and lysine residues of the ELPs. These results suggest that THPP crosslinking may be a biocompatible strategy for the in situ formation of crosslinked hydrogels.