The simplified technique of high resolution two-dimensional polyacrylamide gel electrophoresis: biomedical applications in health and disease

The application of our simplified technique of high resolution two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) to human body fluids is reviewed. Serum/plasma protein changes associated with alcohol abuse, familial dyslipoproteinemia ("fish-eye" disease), and myocardial infarction are demonstrated. High resolution 2-D PAGE of amniotic fluid, cerebrospinal fluid, urine, and saliva is shown with reference to the work of others, and the detection of pink-violet staining "lumicarmines" in sweat and tear fluid is reported for the first time. General aspects relating to the methodology are discussed. These include sample preparation, the choice of electrophoresis conditions (denaturing or nondenaturing) and detection method (Coomassie Brilliant Blue or silver), and the effects of native protein pretreatment with sodium dodecyl sulfate prior to silver staining or isoelectric focusing gel shrinkage in glycerol prior to second-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis.     

New tetra-aryl and bi-aryl porphyrins bearing 5,15-related fluorenyl pendants: the influence of arylation on fluorescence

The new tetra-aryl trans-A₂B₂-porphyrin with two fluoren-2-yl and two phenyl groups at the meso-positions has been synthesized and characterized, together with the analogous bi-aryl trans-A₂-porphyrin incorporating only the fluorenyl groups. The photophysical properties of these new compounds in solution are reported. The two additional phenyl groups in the A₂B₂ porphyrin stabilize the first excited singlet state by approximately 500 cm⁻¹ compared to the A₂ system, as revealed by the red-shift of the absorption Q bands and of the fluorescence emission bands. Both compounds display enhanced emission quantum yields compared to tetraphenylporphyrin: the augmentation is higher for the tetra-aryl than for the bi-aryl system, although not as high as for tetrafluorenylporphyrin. Fluorescence lifetime measurements of the series of four compounds suggest that the trends can be interpreted in terms of the larger influence of fluorenyl over phenyl groups in increasing the fluorescence radiative rate constant of the porphyrin, k_f.     

Photolithographic synthesis of cyclic peptide arrays using a differential deprotection strategy

We report here a strategy for the photolithographic synthesis of diverse, spatially addressable arrays of cyclic peptides which employs a differential deprotection strategy for the combinatorial addition of side chains to a pre-fabricated cyclic core.     

Dilute solution properties of a polyurethane. I. Linear polymers

A linear polyurethane of high molecular weight was prepared in solution by the polyaddition of equimolar amounts of ethylene glycol and methylene bis(4-phenyl isocyanate). The polymer was fractionated by using a direct sequential extraction procedure, with a solvent–nonsolvent system consisting of N,N′-dimethylformamide (DMF) and acetone (A). The resulting fractions were characterized by viscosity and lightscattering measurements. The relationship between the intrinsic viscosity and molecular weight was found in DMF at 25°C. to be [η] = 3.64 × 10^?4M^0.71. The unperturbed polymer chain dimensions were determined from intrinsic viscosity measurements carried out under experimentally determined theta conditions.     

Electron-transfer polymers. XXIX. Copolymerizability of vinylhydroquinone derivatives

Ten vinylhydroquinone and one vinyl resorcinol derivatives are compared, particularly with respect to NMR spectra and copolymerizability with styrene. They are vinylhydroquinone dimethyl ether (I), vinyl-O,O′-bis(1-ethoxyethyl)hydroquinone (II), vinylhydroquinone di(2-pentyl)ether (III), 4-vinyl resorcinol bismethoxymethyl ether (IV), 2-vinyl-5-methylhydroquinone dimethyl ether (V), 2-vinyl-5-methyl-O,O′-bis(1-ethoxyethyl)hydroquinone (VI), 2-vinyl-6-methylhydroquinone dimethyl ether (VII), 2-vinyl-5-tert-butylhydroquinone dimethyl ether (VIII), 2-vinyl-5-chlorohydroquinone dimethyl ether (IX), 2-vinyl-3,6-dimethylhydroquinone dimethyl ether (X), and 2-vinyl-3,5,6-trimethylhydroquinone dimethyl ether (XI). All the vinyl protons have almost the same coupling constants. Though subtle distinctions are found among all the spectra, they can in general be put into two groups on the basis of the chemical shifts. Let the hydrogen on carbon-1 of the vinyl group be A, the hydrogen cis to A be B the hydrogen trans to A be C, then in the first group, (I) through (IX), the chemical shifts (τ) are (A) 3.02 ± 0.08, (C) 4.41 ± 0.05, and (B) 4.87 ± 0.07, and in the second group, (X) and (XI), they are (A) 3.30 ± 0.03, (C) 4.49 ± 0.01, and (B) 4.59 ± 0.03. It is supposed that in (X) and (XI) the vinyl group is out of the plane of the ring, because of the two ortho substituents, and this conformation is reflected in the NMR data. Ultraviolet spectra are consonant with this interpretation, since the λ_max of (X) and (XI) correspond closely with those of nonvinyl reference compounds, while those of (II), (V), and (VIII) are shifted to longer wavelengths. When these compounds are copolymerized separately with styrene, the behaviors are classifiable into the following three groups, where r₁ and r₂ are monomer reactivity ratios with styrene as the first monomer: (i) r₁ < 1 and r₂ < 1 for compounds (II) and (III) and the reference compound O,O′-dibenzoylvinylhydroquinone, (ii) r₁ < 1 and r₂ > 1 for compounds (I), (V), (VII), (VIII), (IX), and (iii) r₁ > 1 and r₂ = 0 for compounds (X) and (XI). These behaviors are correlated with the effect of electronegativity of groups on the stability of the radical at the growing end of the chain and with the simultaneous effects of steric hindrance.     

Self-complementary

Three [3]catenanes with cavities large enough to accommodate aromatic guests have been designed and synthesized (yields = 5-20 %) by means of kinetically controlled self-assembly processes. The X-ray structural analysis of one of three [3]catenanes confirmed the presence of a rectangular cavity (dimensions = 7 x 11 A) lined by pi-electron-rich recognition sites and hydrogen-bond acceptor groups. In spite of their apparently ideal recognition features, none of these [3]catenanes bind guests incorporating a pi-electron-deficient bipyridinium unit. However, the template-directed syntheses of the [3]catenanes also produce, in yields of 2-23%, [2]catenanes incorporating a 1,5-dioxynaphtho[38]crown-10 interlocked with a bipyridinium-based tetracationic cyclophane. The X-ray structural analyses of two of these [2]catenanes revealed that a combination of [pi...pi] and [C-H...pi] interactions is responsible for the formation of supramolecular homodimers in the solid state. 1H NMR spectroscopic investigations of the four [2]catenanes demonstrated that supramolecular homodimers are also formed (Ka= 17-31M(-1), T= 185 K) in (CD3)2CO solutions. Dynamic 1H NMR spectroscopy revealed that the 1,5-dioxynaphtho[38]crown-10 and tetracationic cyclophane components in the four [2]catenanes and in the three [3]catenanes circumrotate (deltaGc(not equal to) = 9-14 kcal mol(-1)) through each other's cavity in (CD3)2CO. Similarly, the 1,5-dioxynaphthalene and the bipyridinium ring systems rotate (deltaGc(not equal to) =10-14 kcal mol(-1)) about their [O...O] and [N...N] axes, respectively, in solution.     

Application of Molecular Weight and Particle Growth Measurements in Continuously Uniform Latices to Kinetic Studies of Styrene Emulsion Polymerization

It is possible to generate, in specially formulated styrene emulsion polymerizations, latices in which the monomer—polymer particles are uniform through all stages of growth. These latices are kinetically similar to their polydispersed counterparts and can therefore be used as model systems in generalized kinetic studies of emulsion polymerization. The most important feature of these systems is the fact that the particles are uniform throughout the reaction with regard to all intrinsic properties and rate processes, and the particles can be characterized by this complete, continuous uniformity. Certain remarkably simple, but precise, relationships exist between the overall, measurable kinetic parameters and the individual particle kinetic parameters, thereby resulting in a heretofore unrealized analytic accessibility. Molecular weight kinetic analyses are an order of magnitude more accurate than in non-uniform systems. Application of these continuously uniform systems in actual kinetic studies indicates an inconsistency in the current concepts of emulsion polymerization, i.e., the generation of polymer at a constant molecular weight is predicted while an increase of several fold is observed. Before the situation can be clarified, further studies with continuously uniform systems are needed to evaluate molecular weight development, molecular weight distribution, and molecular structure and also to re-evaluate the rate and diffusion processes which control these structural features.     

Structural characterization of lipopeptide biomarkers isolated from Bacillus globigii

Spectra obtained using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry of Bacillus globigii (Bacillus subtilis niger) spores, vegetative cells and the culture supernatant show a cluster of biomarkers centered at a molecular mass of 1478 Da. Three biomarkers were isolated from the cell-free culture supernatant by solid-phase extraction and reversed-phase high-performance liquid chromatography, and characterized using various kinds of mass spectrometry. A Fourier transform mass spectrometer with a MALDI source was used to determine the monoisotopic protonated masses at 1463.8, 1477.8, and 1505.8 Da in order of elution. The mass differences of 14 and 28 Da suggest that they are homologous molecules. Alkaline hydrolysis of each species showed that it contained a lactone linkage. Strong acid hydrolysis released a fatty acid from an amide bond, consistent with a lipopeptide. A quadrupole time-of-flight instrument with a nanospray source was used to sequence the hydrolyzed forms of the three biomarkers. The cyclic lipopeptides were found to have amino acid sequences identical with those in fengycins and plipastatins, antimicrobial compounds with phospholipase inhibitor activity, previously identified in related species of Bacillus subtilis and Bacillus cereus.     

On-line storage and retrieval of chemical information. II. Substructure and biological activity searching

An improved interactive system for searching substructure and biological activity data has been developed. Features of the system include a two-level substructure search (fragment screen and atom by atom) and an expanded biological activity data base. The system operates on a file of about 150 000 compounds.