PHOTOINACTIVATION OF CATALASE

Abstract— Inactivation of catalase with visible light (>400nm) has been studied in purified bovine liver catalase and in peroxisomal catalase in the mitochondrial fraction of rat liver. Light corresponding to that of maximal absorbance of the heme site (405 nm) was most effective in inactivation. Although photoinactivation is O₂ dependent, scavengers of OH radical, ¹O₂ and O⁻₂ did not protect against loss of activity in either system. Superoxide dismutase partially protected purified catalase added into the mitochondrial fraction system. However, complete protection of catalase was afforded by low concentrations of substrates such as formic acid or methanol which rapidly convert Compound I to Ferricatalase.     

Chemicals from forest products by supercritical fluid extraction

Supercritical acetone or methanol extraction of wood gave liquid products with a maximum yield of 74%. Approximately 5% of these complex products was identified as substituted guaiacols and levoglucosan. Acetone extract could substitute for 30% of the phenol in phenolic resins.

Resin and fatty acids were extracted from southern pine and waxes from Douglas-fir bark using supercritical carbon dioxide, nitrous oxide, propane or ethylene. Of these, propane and nitrous oxide gave the best yields.     

Stereoselective synthesis of 4-hydroxy-2-phenylproline framework

Highly diastereoselective (>20:1) bromo-lactonization of N-sulfonyl-2-allyl-2-phenylglycine methyl ester (11) was observed. Successive treatment of the chiral lactone with MeONa gave the desired (2S,4R)-4-hydroxy-2-phenylproline derivative in high yield without erosion of the diastereoselectivity. The starting chiral non-racemic compound (5) was prepared from the racemic 2-phenylglycine using a classical kinetic resolution (crystallization), an asymmetric phase transfer alkylation, and an enzyme-catalyzed kinetic resolution.     

Using pulse shape discrimination to sort individual energy deposition events in a germanium crystal

A fast digital oscilloscope based pulse shape discrimination (PSD) system has been tested with intrinsic germanium detectors large enough to allow ionizing events which generate localized electron-hole pairs at a single site to be segregated from those depositing energy at several different sites in the crystal. Drift velocities of the electrons and holes result in pulses several hundred nanoseconds long. Since the electric field varies by almost a factor of 10 between the outer and inner surfaces, collection of electrons and holes can frequently be dinstinguished, and pulses due to multi-site events can be distinguished from single site events.     

CAROTENE and CYTOCHROME C DEPENDENT SURVIVAL KINETICS IN RESPONSE TO HIGH INTENSITY VISIBLE LIGHT IN THE SMUT FUNGUS Ustilago violacea

Abstract— Exposure of variously pigmented strains of Ustilago violacea to high intensity incandescent radiation resulted in the generation of three types of survival curves. High carotene, low cytochrome c containing strains of U. violacea were generally characterized by linear type I survival curves with slopes approximately equal to zero. Strains which lacked carotenes were characterized by exponential decay type II survival curves. A third survival curve, type III was observed with carotene accumulating strains which also contained large amounts of cytochrome c. The type III curves are characterized by an initial loss of viability, similar to the type II curves, followed by a recovery period, with eventual stability in survival. The survival curve type appears to be dependent on the relative mg quantities of cytochrome c and carotenes in the cells. Strains with carotene/cytochromec ratios of0–1 × 10^-1,3–15× 10^-1 and l6 × 10^-1 and above had type II, type III and type I survival curves, respectively.     

Study of cross-conjugated iso-polytriacetylenes and related oligoenynes

Two series of monodisperse cross-conjugated oligomers based on enyne repeat units have been realized. The first class of molecules, iso-polytriacetylenes (iso-PTAs, 2), was divergently synthesized using an iterative sequence of palladium-catalyzed cross-coupling reactions of vinyl triflate 5 with terminal alkynes. The second series of oligoenynes (17-20) are based on an octatetrayne backbone, and result from homocoupling of the differentially protected iso-PTA oligomers 8-11. The longest member of this series, 20, spans ca. 5.6 nm from Si atom to Si atom and is composed of a contiguous sequence of 44 sp and sp(2) carbons. The lowest energy electronic absorption band for iso-PTA dimers in the progression 13 --> 9 --> 16 is consistently red-shifted as a result of extending the cross-conjugated structure. A similar comparison within each series (i.e., 16, 6-7, or 17-20), however, suggests little effect on the electronic characteristics of these molecules as oligomer length is increased. The solid-state properties of one derivative, 17, are also described.     

OXYGEN-DEPENDENT PHOTOSENSITIVITY and MITOTIC RECOMBINATION IN THE SMUT FUNGUS Ustilago violacea

Abstract— The effect of high intensity incandescent radiation on survival and mitotic recombination in the phlph + diploid strain of Ustilago violacea was studied with and without atmospheric O₂. In the presence of atmospheric O₂, strain phlph+ was characterized by photokilling to approximately 50% survival, and induction of mitotic recombination to about 60% by 90 min of light exposure. No photokilling and little induction of mitotic recombination were observed when light exposure was carried out in an 0₂ depleted environment. Photokilling and photo-induced mitotic recombination in U. violacea may be due to DNA damage or repair in response to a photosensitized reaction, involving an endogeneous photosensitizer.     

Theoretical results for the excited states of ozone

On the basis of ab initio calculations (configuration interaction and generalized valence bond), we find eight excited states of ozone with vertical excitation energies less than 7 eV. Using these results the various experimental transitions are assigned. One state has an equilateral triangle as the minimum energy geometry (1.5 eV above the ground state).