Antimicrobial nano-assemblies of tryptocidine C, a tryptophan-rich cyclic decapeptide, from ethanolic solutions.

Tryptocidine C (TpcC), a Trp-rich cyclodecapeptide is a minor constituent in the antibiotic tyrothricin complex from Brevibacillus parabrevis. TpcC possesses a high tendency to oligomerise in aqueous solutions and dried TpcC forms distinct self-assembled nanoparticles. High-resolution scanning electron microscopy revealed the influence of different ethanol:water solvent systems on TpcC self-assembly, with the TpcC, dried from a high concentration in 15% ethanol, primarily assembling into small nanospheres with 24.

Structures of the 2-nitrophenol alkali complexes in solution and the solid state.

The materials studied in this investigation were aqueous solutions (0.02-25.0 mM) of the salts of alkali metal ion (Me(+)) and 2-nitrophenol (2-NP).

Two dimensional crystallization of three solid lipid A-diphosphate phases.

Surface-tension-induced liquid-crystal growth of monomeric lipid A-diphosphate in aqueous dispersions is reported as a function of concentration, (c), and temperature, (T), and at low ionic strength (10(-3) M). As the temperature was varied, a solid-liquid transition was revealed in the surface layer at a fixed lipid A-diphosphate bulk concentration. Here, the development of different two-dimensional (2-d) faceted crystal morphologies was observed and, as growth proceeded, these faceted 2-d crystals became unstable.

Phase transformations in lipid A-diphosphate initiated by sodium hydroxide.

The nature of the fluid phase transitions of charged-stabilized spherical lipid A-diphosphate clusters in aqueous dispersions was explored using a combination of small-angle X-ray scattering (SAXS) and electron microscopy. In contrast to previous studies, rather than removing NaCl, NaOH was added to the dispersions to promote crystallization. The fluid phase experiments were carried out employing titrations with mM·L(-1) NaOH (c(S)), along with variations in the particle-number density, n.

Studies on structures of lipid A-monophosphate clusters.

Single crystalline clusters of lipid A-monophosphate were grown from organic dispersions containing 5-15% (v/v) water at various volume fractions, φ, and temperatures. The morphology of the single lipid A-monophosphate crystals was either rhombohedral or hexagonal. The hexagonal crystals were needlelike or cylindrical in shape, with the long dimension parallel to the c axis of the unit cell.

Two new colloidal crystal phases of lipid A-monophosphate: order-to-order transition in colloidal crystals.

A study of the structure of stable regular-shaped nanocrystals of hexa-acylated (C(14)) lipid A-monophosphate from Escherichia coli was carried out using dilute electrostatically stabilized aqueous dispersions at low ionic strength (I=1.0x10(-5)M NaCl). An order-to-order transition of colloidal clusters of lipid A-monophosphate was found at two volume fractions: phi=5.

14N and 81Br quadrupolar nuclei as sensitive NMR Probes of n-alkyltrimethylammonium bromide crystal structures. An experimental and theoretical study.

This is the first time a comprehensive study has been carried out on n-alkyltrimethylammonium bromide salts using (14)N and (81)Br solid state NMR, X-ray diffraction, and theoretical calculations. The investigation represents a necessary step toward further (14)N and (81)Br NMR characterization of the environment of cationic and anionic groups in materials, accounting for the amphiphilic properties of cationic surfactants. The NMR spectra of five C(x)H(2x+1)(CH(3))(3)N(+)Br(-) polycrystalline samples with different n-alkyl chain lengths (x = 1, 12, 14, 16, 18) were recorded and modeled.

Nucleation of calcium carbonate as polymorphic crystals in the presence of lipid A-diphosphate.

The well-defined structure of lipid A-diphosphate in aqueous solutions provides a way of observing the formation of calcium carbonate crystals. The crystals are either tetrahedral or rhombohedral calcite at a volume fraction of phi = 5.4 x 10 (-4) at pH 5.

The phase diagram of charged colloidal lipid A-diphosphate dispersions.

Small-angle X-ray-scattering, light-scattering, and electron microscope experiments were used to determine the phase transitions of colloidal lipid A-diphosphate aqueous dispersions. The phases detected were a correlated liquid phase, a face-centered cubic (Fd3m) and a body-centered cubic (Im3m) colloidal crystal phase and a new glass phase. These experimentally determined phases were shown to be in accord with theoretically predicted equilibrium phases.

Observations of liquidlike order of charged rodlike lipid A diphosphate assemblies at pH 8.5.

A new structural form of charged lipid A diphosphate, with a molecular weight of 5.9x10(6) Da and a rodlike shape (L=800 nm), was found in aqueous solutions at pH 8.5.

Ordering of lipid A-monophosphate clusters in aqueous solutions.

In this investigation, a study of the self-assembly of electrostatically stabilized aqueous dispersions of nanometric lipid A-monophosphate clusters from Escherichia coli was carried out in three different volume-fraction regimes. The experimental techniques used in the investigation were osmotic pressure, static and quasielastic light scattering, scanning electron microscopy and transmission electron microscopy, and small-angle x-ray scattering. Experiments were carried out at low ionic strength (I=0.

Elusive forms and structures of N-hydroxyphthalimide: the colorless and yellow crystal forms of N-hydroxyphthalimide.

A comprehensive structural characterization of the colorless and yellow forms of N-hydroxyphthalimide (NHP), the deuterated form (NDP), and the ethoxylated form (ethoxy-NHP) has been carried out using single-crystal X-ray diffraction, FTIR and Raman spectroscopies, and scanning electron microscopy. Both NHP and NDP forms crystallize in the monoclinic space group (P21/c, No. 14).

The liquidlike ordering of lipid A-diphosphate colloidal crystals: the influence of Ca2+, Mg2+, Na+, and K+ on the ordering of colloidal suspensions of lipid A-diphosphate in aqueous solutions.

A comprehensive study was performed on electrostatically stabilized aqueous dispersion of lipid A-diphosphate in the presence of bound Ca2+, Mg2+, K+, and Na+ ions at low ionic strength (0.10-10.0-mM NaCl, 25 degrees C) over a range of volume fraction of 1.

Physicochemical and structural studies of triamterene.

It has been shown by several physicochemical techniques that the existence of different crystal forms of triamterene, as well as the crystalline products from different solvents with distinct differences in melting points, does not necessarily imply polymorphic crystal forms. The crystalline structure for triamterene is reported herein, revealing a N,N-dimethylformamide molecule and a water molecule within the crystal lattice. Triamterene crystallizes in a face-centered orthorhombic space group, Fdd2 (#43), when grown from aqueous solutions of dimethylformamide (N,N-DMF).

Structure of tyrocidine micelles in isotropic aqueous solution.

Aqueous solutions of tyrocidine B, iodoacetyltyrocidine B, and diiodotyrocidine B in 40% H2O:60% ethanol (w/w) were investigated by analytical ultracentrifugation, light scattering, and small-angle X-ray scattering techniques. A reasonable hydrodynamic description of the aggregates of molecular weight 28,600 is a rod with a length of 170 A and a diameter of 30 A; this description is consistent with the X-ray scattering data. Over a broad range of concentrations, inelastic light scattering measurements and small-angle X-ray scattering experiments provide the same hydrodynamic values (e.

Structure of phenylbutazone and mofebutazone in the crystalline state and in solution.

The crystal structure of the keto form of phenylbutazone has been determined and compared with the molecular conformation of mofebutazone. The pronounced differences between these two structures are the conformation of the n-butyl side chain (which is extended and in trans conformation for mofebutazone, however, bent at the C gamma-position with hydrogen bonding of the gamma-hydrogen to the carbonyl C(3)--O(1) for phenylbutazone), and the in-plane conformation of the phenyl group with respect to the heterocyclic ring system in mofebutazone compared with two benzene rings at N(1) and N(2) which are almost perpendicular to the pyrazolidin-(3,5)-dione ring. Preliminary X-ray data reveal that the structures of the alkali enolates of both compounds are difficult to solve because the crystal quality is insufficient and highly disordered.

Size and shape of the alpha subunit of the (Ca,Mg)-dependent adenosinetriphosphate from Escherichia coli in solution in the presence and absence of ATP.

The alpha subunit of the (Ca, Mg)-dependent ATPase from Escherichia coli was studied in solution by means of X-ray scattering experiments at variable contrast and in the presence of ATP. The experiments were carried out on an absolute scale in the range of (45.0 nm-1) less than h less than (1.