COMPARISON OF THE EFFECTS OF ULTRAVIOLET RADIATION ON THE INTRACELLULAR CATALASE OF AEROBIC AND ANAEROBIC YEAST

Abstract— Suspensioris of aerobic and anaerobic yeast were subjected to ultraviolet radiation (principally 254 mµ ) under closely comparable experimental conditions, and changes in the level and in the temperature dependence of their catalase activity were determined. Qualita tively, the effects of U.V. on the enzyme of the anaerobic cells were similar to those on that of the aerobic cells. The effect of U.V. on the anaerobic catalase differed from that on the aerobic enzyme in the following respects: I, a considerably greater dose of U.V. was necessary in order to attain the maximum activity and the minimum activation energy of the enzyme-substrate system; 2, a far greater dose was required before appreciable photoinactivation of the maxi mally active enzyme occurred; 3, photoinactivation proceeded at less than one-half the rate; 4, the u.v.-induced increase in the catalase activity of the suspension was virtually complete before appreciable reduction in activation energy occured. The first three of these differences were interpreted in terms of a model, which pictures the anaerohic catalase as being tightly bound to an intracellular chromophore group.     

The dependence of the branching ratio in the F+HD reaction on the initial rotational state of HD

Both classical trajectory and quantal scattering calculations indicate that the branching ratio in the F+HD reaction varies considerably with the initial rotational state of HD. Information theory argues that this variation must be reflected in the distribution of the reaction products. Hence, given the (normalized) product distribution for each reaction path one should be able to predict the dependence of the branching ratio on the state of the reagents. The trajectory computations of Muckerman are used to illustrate the procedure. First the dynamic constraint is identified and then the reaction probability matrix is constructed. The determination (“synthesis”) of the matrix, in terms of the given constraint invokes information theory and, in particular, the procedure of maximising the entropy. The branching ratio is readily computed from the elements of the probability matrix. Very good agreement is obtained between the trajectory-computed and the synthetic branching ratio for all initial rotational states of HD.The F+HD reaction has three possible final arrangement channels (one nonreactive and two reactive ones) and is used to illustrate the structure of the reaction probability matrix and the associated entropy measures.     

The structure of plasma-polymerized toluene: A solid-state 13C-NMR study of isotopically labeled polymers

A detailed magic angle spinning ¹³C-NMR investigation of the intractable polymer prepared by plasma polymerization of toluene and isotopically labeled toluene led to a proposed model for the structure of the polymer and suggested some of the likely processes that occur in the gas phase leading to film formation. From the ¹³C spectra four resolved resonances permitted the determination of the contribution of nonprotonated and protonated unsaturated as well as methyl and other aliphatic carbons to the polymer structure. Specific ¹³C isotopic labeling of the methyl and phenyl C-1 toluene carbons in the injected liquid vapor allowed the destination of these carbons in the deposited polymer to be traced. The dominant structure is derived primarily from two precursors: benzyl radical and toluene itself. The ¹³C data further requires a net saturation of ca. 30% of the toluene double bonds and a net displacement of hydrogen by carbon on ca. 20% of the toluene ring carbons.     

Chemical shielding anisotropy of 13C and 15N in acetonitrile

High resolution ¹³C and ¹⁵N NMR spectra have been obtained for powdered CH₃CN. The presence of resolved dipolar structure in the ¹³C spectra permits the conclusion that the symmetry axis of the ¹³C shielding tensor lies along the CN bond direction.     

Synthesis of persulfate containing poly (N-vinyl-2-pyrrolidone) (PVP) hydrogels in aqueous solutions by γ-induced radiation

The effect of ⁶⁰Co γ-irradiation on aqueous solutions of poly(N-vinyl-2-pyrrolidone) (PVP) in the presence of persulfate anion has been investigated. The gelation dose of PVP and persulfate containing PVP aqueous solutions has been determined. At low concentrations of persulfate (1.00–3.50%), gelation percentages exhibited a decreasing trend by increasing persulfate content in aqueous solutions of the polymer. The gelation doses of persulfate containing polymer solutions were calculated by the Charlesby–Pinner equation. It was observed that the gelation dose values were shifted to higher values by increasing persulfate concentration in solution. The ratio of the chain scission and crosslinking yields (G(s)/G(x)) was also determined. The results showed that the G(s)/G(x) ratios were smaller than one for PVP aqueous solution system, whereas those obtained for persulfate containing PVP aqueous solutions were higher than unity. The results implied that the chain scission of polymer is more effective than crosslinking in the presence of persulfate. Mechanism of the crosslinking and/or degradation and structure–property relationship of PVP and PVP/persulfate hydrogel systems were investigated by Fourier transformation infeared and thermal analysis (differential scanning calorimetry, thermal gravimetric analysis and differential thermai analysis) methods.