Enzymatic polymerizations using surfactant microstructures and the preparation of polymer-ferrite composites

Applied Biochemistry and Biotechnology - Horseradish peroxidase has been used as a biocatalyst to synthesize a polymeric material from alkyl-substituted phenols. The synthesis is carried out in a...     

Synthesis and characterization of polymers produced by horseradish peroxidase in dioxane

Polymers were synthesized from substituted phenolic and aromatic amine compounds with hydrogen peroxide as the source of an oxidizing agent and horseradish peroxidase enzyme as the catalyst. The polymerization reaction was carried out in a monophasic organic solvent with small amounts of water at room temperature. Conditions for the synthesis of polymers with respect to reaction time and yield were studied with a number of monomers at different concentrations and in solvents with different buffers with pH range of 5.0–7.5. Physical and chemical properties of these homo-and copolymers were determined with respect to melting point, solubility, elemental analysis, molecular weight distribution, infrared absorption (including FTIR), solid-state ¹³C nuclear magnetic resonance, thermal gravimetric analysis, and differential scanning calorimetry. The enzyme catalyzed reactions produced polymers of molecular weight greater than 400,000 which were further fractionated by differential solubility in solvent mixtures and the molecular weight distribution of the polymer fractions were determined. In general, the polymers synthesized have low solubilities, high melting points, and some degree of branching.     

Electron-impact fragmentation of aliphatic polynitro compounds

The mass spectra of two series of aliphatic polynitro compounds are reported and discussed. The fragmentation patterns of aliphatic nitro and polynitro compounds are similar in that no appreciable molecular ion current is observed; however, there are several other features in the fragmentation of aliphatic polynitro compounds which differ from that of nitroalkane spectra. Both series of compounds studied-C(NO₂)_x(CH₃)_4?x, where x = 4 to 0 and C₂(NO₂)_x(CH₃)_6?x, where x = 6,4,2-show a decrease in the number and intensity of alkylions with an increase in the NO⁺ and NO₂⁺ ion current as x increases. The main ions resulting from the more nitrated compounds are [NO]⁺, [NO₂]⁺, [CO₂]^+. and [CH₃CO]⁺, whose noncharged counterparts are the principal species produced in the detonation of these compounds. This similarity of the products of the two processes suggests the use of mass spectroscopy for the investigation of the initial explosive processes. The principal fragmentation pathways of the polynitroalkanes have been elucidated by exact mass measurements and the observation of metastable ion transitions.     

PHOTOREVERSION VON VIER GRUPPEN UV-INDUZIERTER MUTATIONEN ZUR GIFTRESISTENZ IM NICHTPHOTOREAKTIVIERBAREN E. COLI

Abstract— In the non-photoreaclivable bacterial strain E. coli B/phr^-/MC2 the photoreversion of four groups of u.v.-induced mutations were investigated. They lead to resistance to Chloramphenicol (2 mg/l; "C"), Penicillin (13 or 16 mg/l; "P13" and "P16") or Streptomycin (3 mg/l; "S"). The u.v.-dose curve is concave for the C-mutations (two to three hits), about linear for P13 and S, and they reach peaks and decrease at high u.v.-doses. Though no photoreactivation of killing (PR) is present there is photoreversion of all four types of mutations (PRM). At u.v.-doses below the peaks in average about 43 per cent mutations are photoreversible. At high u.v.-doses the curves with light-post treatment (L) cross the darkcurves (D). In the photoreactivable strain B/r (by the spontaneous mutation MC2 to Mitomycin-resistance strain B/phr^- was made about as u.v.-resistant as B/r is) the photoreversion of the mutation groups C, P13 and P16 (S was not investigated here) was much higher, in average about 77 per cent at low doses. It is assumed that the difference in PRM of about 34 per cent between both strains is due to a PRM-mechanism present in B/r but not in B/phr^-/MC2; this mechanism may be the photoreactivating enzyme that opens thymine-dimers. The PRM in B/phr-/MC2 must then be due to a second mechanism which is probably not the dimer opening enzyme. It may be the same mechanism as in the case of mutations of phage kappa which are induced by u.v. and reversed partially by light, both extra cellularly. The premutations giving this second type of PRM may perhaps be cytosine-hydrate in the DNA. Tn average about 23 per cent mutations of B/r are photostable. Since this ratio decreases with low u.v.-doses in the C-mutations and increases in P13 and in P16 probably two types of photostable premutations seem to exist.