Product analyses and crosslink mechanism of plasma-polymerized methyl methacrylate

Plasma-polymerized methyl methacrylate (PPMMA) film was produced by a radio-frequency glow discharge of methyl methacrylate (MMA) gas with argon. PPMMA deposited under a plasma of mild energy was separated into a soluble fraction (sol-PPMMA) and an insoluble matrix (insol-PPMMA), which is highly crosslinked, by solvent-extraction and filtration. The chemical structure of the sol-PPMMA was determined by pyrolysis/gas chromatography, IR spectroscopy, ¹H-NMR, ¹³C-NMR, and elemental analysis techniques. On the other hand, the structure of the insol-PPMMA was examined with IR spectroscopy, ¹³C-NMR with CP/MAS method, and elemental analysis. The crosslinking mechanism in the plasma polymerization of MMA is discussed on the basis of product analyses of the sol-PPMMA and the insol-PPMMA.     

FLUORESCENCE OF 1-DIMETHYLAMINONAPHTHALENE-5-SULFONATE AND PYRENE-1-SULFONATE CONJUGATED TO BACTERIORHODOPSIN

Abstract— Two fluorescence probes, 1-dimethylaminonaphthalene-5-sulfonylchloride and pyrene-1-sulfonylchloride, were conjugated to the protein in purple membrane and fluorescence intensity and anisotropy were measured as a function of temperature. The anisotropy of the 1-dimethyl-aminonaphthalene-5-sulfonate conjugate showed a characteristic temperature dependence, in which, the anisotropy is constant at 0.22 ± 0.01 until 25-30°C and decreases above 30°C. The fluorescence intensity, however, varies linearly with temperature. These results imply that the transition is due to bacteriorhodopsin in the trimer.     

QUATERNARY STRUCTURE OF PEA PHYTOCHROME I DIMER STUDIED WITH SMALL-ANGLE X-RAY SCATTERING and ROTARY-SHADOWING ELECTRON MICROSCOPY

Abstract— The quaternary structure of pea phytochrome type I (PI) dimer in the red-light-absorbing form was studied by small-angle X-ray scattering (SAXS) technique and rotary-shadowing electron microscopy. Structural parameters for PI 114 kDa chromopeptide dimer and its tryptically digested N-terminal 59 kDa chromopeptide monomer, such as average electron density, molecular volume and the second moment of electron density distribution, were determined in terms of SAXS using the contrast variation method. Furthermore, by means of model simulation for the scattering profiles of the chromopeptides, most plausible structural models for both peptides were constructed. The distance between the chromophoric domains was estimated to be about 70 A in the resultant model for 114 kDa chromopeptide dimer. Furthermore, the model was consistent with the electron-micrographic images of both the intact PI dimer and the PI 114 kDa chromopeptide dimer, so that the N-terminal 7 kDa fragment did not significantly contribute the low-resolution images of the dimer.     

Alternating copolymerization of 1- and 2-vinylnaphthalene with methyl methacrylate by using diethylaluminum chloride

The alternating copolymerization of 1- and 2-vinylnaphthalene (1-VNap and 2-VNap) with methyl methacrylate (MMA) by using diethylaluminum chloride (Et₂AlCl) in toluene at 0°C has been studied. No polymerization could occur without Et₂AlCl, and alternating copolymers were obtained only when an equimolar amount of Et₂AlCl with MMA was supplied. Through ¹H-NMR analyses on both dyad and triad of alternating deuterated 1- and 2-α-d-VNap–MMA copolymers, each configuration could be described successfully by a single parameter, coisotacticity σ, whose value was estimated as 0.41 for the former and 0.56 for the latter copolymer, respectively. A rather low coisotacticity of copoly(1-VNap–MMA) was explained in the terms of steric effect (peri effect) of 1-VNap monomer.     

Novel ring transformation reactions of xanthine derivatives

The novel ring transformation reactions were found in the reactions of 1,3,7,9-tetra-alkyl-8,9-dihydroxanthines and acetylenic compounds. The reaction of the dihydroxanthine with DMAD gave a propellane type compound and with methyl propiolate afforded the similar type compound and a pyrimido[4,5-b]diazepine derivative. The mechanism of these reactions was also discussed.     

Agarose isoelectric focusing for the detection of many isoforms and high molecules in muscle protein analysis

Two-dimensional gel electrophoresis with agarose in the first dimension was established. The technique was reported previously and was now much improved without changing the basic procedure, presenting "a protein map" of chicken skeletal muscle, including almost all components such as myosin heavy chains (200 kDa) and dystrofin (400 kDa). Application of this technique for the analysis of all components was also successful with the liver and lens. Since large molecules can get into the agarose in the first dimension, the study on protein interaction was also reported with troponin components as a model system.     

Preparation of crystalline polyamides by the alternating copolymerization of aziridines and cyclic imides

The copolymerization of aziridines and cyclic imides was studied. Aziridines copolymerized alternately with cyclic imides to give crystalline polyamides. Ethylenimine and succinimide copolymerized to nylon 2,4, melting near 300°C., without any catalyst. Similarly, the corresponding crystalline polyamides were obtained from the systems of 1,2-propylenimine–succinimide, ethylenimine–glutarimide, and ethylenimine–phthalimide. The copolymerization of aziridines and cyclic imides in the presence of BF₃OEt₂ gave a copolymer which was rich in aziridine units, whereas, the addition of triethylamine had no influence on the copolymer composition. A mechanism of copolymerization was proposed based on the facts that N-tetramethylenesuccinamide was obtained by the reaction of pyrrolidine and succinimide, N-acetylethylenimine reacted with acetamide to yield N,N′-diacetylethylenediamine and that the rate of this copolymerization was dependent on the electrophilicity of imide.     

Infrared spectra of the water-nitrogen complexes (H2O)2-(N2)n(n = 1-4) in argon matrices

The infrared spectra of the water-nitrogen complexes trapped in argon matrices have been studied with Fourier transform infrared absorption spectroscopy. The absorption lines of the H20-N2 1:1, 1:2, 1:n, and 2:1 complexes have been confirmed on the basis of the concentration effects. In addition, we have observed a few lines and propose the assignments for the 2:2, 2:3, and 2:4 complexes in the nu1 symmetric stretching and nu2 bending regions of the proton-acceptor molecule, and in the bonded OH stretching region of the proton-donor molecule. The redshifts in the bonded OH stretching mode and blueshifts in the OH bending mode suggest that the hydrogen bonds in the (H2O)2-(N2)n complexes with n = 1-4 are strengthened by the cooperative effects compared to the pure H2O dimer. Two absorption bands due to the 3:n complexes are also observed near the bonded OH stretching region of the H2O trimer.     

Determination of conjugated bile acids in human urine by high-performance liquid chromatography with chemiluminescence detection.

A qualitative and quantitative analysis of the conjugated 1 beta- and 6 alpha-hydroxy bile acids, including common bile acids, in human urine using high-performance liquid chromatography with chemiluminescence detection is described. After extraction of urine with C18 silica cartridges, the bile acids were separated into non-conjugated, glycine, taurine and sulphate fractions by ion-exchange chromatography on a lipophilic gel. Solvolysis of the sulphate was carried out by treatment with trifluoroethanol in acetone containing hydrochloric acid, and the liberated amino acid conjugates were fractionated again. The individual bile acids were separated on a reversed-phase C18 column (Bile Pak II), with detection by an immobilized 3 alpha-hydroxysteroid dehydrogenase enzyme reactor and chemiluminescence reaction of the generated NADH using 1-methoxy-5-methylphenazinium methylsulphate-isoluminol-microperoxidase system. The assay method showed the detection limits ranging from 8 to 250 pmol for the bile acids tested. Analysis of urine samples obtained from newborns, non-pregnant women and women in late pregnancy showed a large difference in bile acid composition and conjugation mode, suggesting that bile acid metabolism is different during fetal and neonatal periods.