Kit for instant 99mTc labeling of the antimicrobial peptide ubiquicidin 29-41

Summary The ubiquicidin 29-41 fragment (UBI) is a cationic antimicrobial peptide. The aim of this study was to develop an instant kit formulation for the preparation of ^99mTc-UBI 29-41 in high radiochemical yield and to evaluate its use as an infection imaging agent in humans. The components were selected to produce a direct ^99mTc labeling, presumably to the amine groups of Lys and Arg7. ^99mTc-UBI 29-41 obtained from the lyophilized kit showed radiochemical purity of >97% with an average target/non-target ratio of 2.3±0.6 in positive infection sites at 2 hours. Kits were stable at 4 °C for over 6 months.     

Effects of Adsorbed Polyaniline on Redox Process on MoO3 Surface

The effects exhibited by adsorbed conducting polyaniline on the redox process on a molybdenum oxide surface were studied. Thermogravimetric results indicate a 4% polyaniline deposition. Cyclic voltammograms of the adsorbed polymer on MoO3 show that polyaniline exerts remarkable effects on the molybdenum blue oxidation-reduction process, with oxidation and reduction potentials of 0.33 and 0.18 V, respectively. This effect strongly enhances the electrode response, and can be used as an important tool in qualitative and/or quantitative determinations of molybdenum in solution as well as in any substrate. Copyright 1999 Academic Press.     

Proton affinity of β-oxalylaminoalanine (BOAA): Incorporation of direct entropy correction into the single-reference kinetic method

A new version of the single-reference-extended kinetic method is presented in which direct entropy correction is incorporated. Results of calibration experiments with the monodentate base pyridine and the bidentate base ethylenediamine are presented for which the method provides proton affinities in excellent agreement with published values and reasonable predictions for the protonation entropies. The method is then used to determine the proton affinity and protonation entropy of the non-protein amino acid beta-oxalylaminoalanine (BOAA). The PA of BOAA is found to be 933.1 +/- 7.8 kJ/mol and a prediction for the protonation entropy of -39 J mol(-1) K(-1) is also obtained, indicating a significant degree of intramolecular hydrogen bonding in the protonated form. These results are supported by hybrid density functional theory calculations at the B3LYP/6-311++G**//B3LYP/6-31+G* level. They indicate that the preferred site of protonation is the alpha-nitrogen atom (PA = 935.0 kJ/mol) and that protonated BOAA has a strong hydrogen bond between the hydrogen on the alpha-amino group and one of the carbonyl oxygen atoms on the side chain.     

Direct observation of cations and polynucleotides explains polyion adsorption to like-charged surfaces

We show an experimental approach for directly observing the condensation of polynucleotides and their electrolyte counterions at a liquid/solid interface. X-ray standing waves (XSW) generated by Bragg diffraction from a d = 20 nm Si/Mo multilayer substrate are used to measure the distinct distribution profiles of the polyanions and simple cations along the surface normal direction with subnanometer resolution. The 1D spatial sensitivity of this approach is enhanced by observing the XSW induced fluorescence modulations over multiple orders of Bragg peaks. We study the interesting divalent cation driven adsorption of anionic polynucleotides to anionic surfaces by exposing a hydroxyl-terminated silica surface to an aqueous solution with ZnCl2 and mercurated poly-uridylic acid (a synthetic RNA molecule). The in situ long-period XSW measurements are used to follow the evolution of both the Zn and Hg distribution profiles during the adsorption process. The conditions and physical mechanisms that govern the observed divalent cation adsorption and subsequent polynucleotide adsorption to an anionic surface are explained by a thermodynamic model that incorporates nonlinear electrostatic effects.     

Chemical and analytical characterization of related organic impurities in drugs

A system is proposed for the classification of related organic impurities in drugs and drug products including among others (separated and non-separated) intermediates, various kinds of by-products, among them products of different side reactions, epimeric/diastereomeric, enantiomeric impurities, impurities in natural products, and finally degradation products. Examples are taken mainly from the author's own experience and from among the named impurities in the European Pharmacopoeia with focus on impurities in hydrocortisone, prednisolone, enalapril maleate, lisinopril, ethynodiol diacetate, pipecuronium bromide, cimetidine, and ethynylsteroids. The methodological aspects of impurity profiling from the detection to the identification/structure elucidation and quantitative determination of impurities are briefly summarized.This paper is Part 23 in the series "Estimation of impurity profiles of drugs and related materials". For Part 22 see ref. [1].     

Cobalt-mediated approach for the synthesis of terpene-based hybrids

[structure: see text] Dicobalt-beta-pinene hybrids of types I and II have been prepared using a Nicholas reaction between propargyl derivatives, obtained from commercial (1R)-(-)-myrtenal, and different aromatic nucleophiles. The method is suitable for the preparation of densely functionalized bio-organometallic natural product-based hybrids, as demonstrated by the preparation of a beta-pinene-neoclerodane hybrid.     

Two-dimensional polyacrylamide gel electrophoresis, with immobilized pH gradients in the first dimension, of barley seed proteins: discrimination of cultivars with different malting grades.

The suitability of high-resolution two-dimensional gel electrophoresis for barley cultivar discrimination and for classification with respect to their malting properties was studied. Seed proteins of 14 barley cultivars with different malting qualities were extracted with urea/dithiothreitol/Nonidet P-40 buffer and subjected to two-dimensional gel electrophoresis with immobilized pH gradients in the first dimension (IPG-DALT). The results of IPG-DALT were compared to the protein patterns obtained by a standard technique, sodium dodecyl sulfate polyacrylamide gel electrophoresis of hordeins. Sodium dodecyl sulfate-gel electrophoresis yielded seven different "B" and four different "C" hordein patterns; "A" and "D" hordein patterns were uniform in all cultivars tested. Four cultivars could be distinguished unequivocally, the others were classified into three groups containing between two and five cultivars. In contrast to these findings. IPG-DALT yielded three different "A", eight different "B", four different "C" and two different "D" hordein patterns. When the "A", "B", "C" and "D" hordein patterns were combined, ten cultivars exhibited unique hordein patterns whereas the remaining ones were classified into two groups containing two cultivars each. Moreover, when albumin and globulin proteins were used for evaluation in addition to the hordeins, all cultivars could be discriminated by IPG-DALT. IPG-DALT, performed on small-scale and/or ready-made gels, proved to be an ideal complementary system to one-dimensional electrophoretic methods for routine seed testing purposes because of its speed, reliability, and simplicity. IPG-DALT was also applied to study the relationship between the different polypeptide patterns and the malting quality. Although cultivars with identical one-dimensional protein patterns but different malting quality could be successfully differentiated by IPG-DALT, a direct correlation between specific protein spots or protein patterns to the malting quality was not found within the cultivars tested.     

Molecular Structure and Conformational Composition of 1-[(Methylthio)methyl]-2-nitrobenzene (MTMNB): A Theoretical and Experimental Study

The conformational composition of gaseous MTMNB and the molecular structures of the rotational forms have been studied by electron diffraction at 130^∘C aided by results from ab initio and density functional theory calculations. The conformational potential energy surface has been investigated by using the B3LYP/6-31G(d,p) method. As a result, six minimum-energy conformers have been identified. Geometries of all conformers were optimized using MP2/6-31G(d,p), B3LYP/6-31G(d,p), and B3LYP/cc-pVTZ methods. These calculations resulted in accurate geometries, relative energies, and harmonic vibrational frequencies for all conformers. The B3LYP/cc-pVTZ energies were then used to calculate the Boltzmann distribution of conformers. The best fit of the electron diffraction data to calculated values was obtained for the six conformer model, in agreement with the theoretical predictions. Average parameter values (r_a in angstroms, angle α in degrees, and estimated total errors given in parentheses) weighted for the mixture of six conformers are r(C–C) = 1.507(5), r(C–C)_{ring, av} = 1.397(3), r(C–S)_av = 1.814(4), r(C–N) = 1.495(4), r(N–O)_av = 1.223(3), ∠(C–C–C)_ring = 116.0–122.5, ∠ C6–C4–C7 = 118.2(4), ∠ C–C–S = 113.6(6), ∠ C–S–C = 98.5(12), ∠ N–C–C4 = 121.9(3), ∠(O–N–C)_av = 116.8(3), ∠ O–N–O = 127.0(4). Torsional angles could not be refined. Theoretical B3LYP/cc-pVTZ torsional angles for the rotation about C–N bond, φ_C−N, were found to be 30.5–36.5^∘ for different conformers. As to internal rotation about C–C and C–S bonds, values of φ_C−C = 68–118^∘ and φ_C−S = 66–71^∘ were obtained for the three most stable conformers with gauche orientation with respect to these bonds. Some conclusions of this work were presented in a short communication in Russ. J. Phys. Chem. 2005, 79, 1701.     

Synthesis and Single Crystal Structure of a New Dinuclear Copper(II) Complex of 1,5-Bis(8-oxaquinoline)-3-methylpentane

A new flexible ligand, 1,5-bis(8-oxaquinoline)-3-methylpentane (C5MeOQ), was synthesized and used in the preparation of the new dinuclear copper(II) complex 1: [Cu₂(μ-OMe)₂(μ-C5MeOQ)(NO₃)₂]. Single crystal X-ray analysis revealed that complex 1 contains dinuclear Cu(II) units with bridging methoxo groups. The ligand, C5MeOQ, takes on a bent conformation in order to connect to and complete the square planar coordination environment of both copper centers; and one of the two Cu(II) centers adopts a distorted square planar configuration as a result of the ligand conformation. The magnetic properties of complex 1 were investigated by variable-temperature magnetic susceptibility measurements in the 100–300 K range. Interestingly, the susceptibility data for complex 1 reveals that the compound is diamagnetic, suggesting the presence of very strong antiferromagnetic coupling interactions between the adjacent Cu(II) centers.