Mechanisms Whereby Mononuclear Copper Proteins Functionalize Organic Substrates

1996 ◽  
Vol 96 (7) ◽  
pp. 2541-2562 ◽  
Author(s):  
Judith P. Klinman
Keyword(s):  
Organic Substrates ◽  
Copper Proteins

scholarly journals Spectroscopic evidence for a photosensitive oxygenated state of ammonia mono-oxygenase

1985 ◽  
Vol 226 (2) ◽  
pp. 499-507 ◽  
Author(s):  
J H Shears ◽  
P M Wood
Keyword(s):  
Metal Ion ◽  
Chelating Agents ◽  
Ammonia Oxidation ◽  
Resting Cells ◽  
Organic Substrates ◽  
Copper Proteins ◽  
Binuclear Copper ◽  
Oxidation Activity ◽  
Copper Site ◽  
Electron Reduction

Photoinactivation of ammonia oxidation by Nitrosomonas europaea cells by near-u.v. light was confirmed and further shown to occur with the same rate constant as loss of bromoethane-oxidation activity. Hydroxylamine oxidation was much less photosensitive. Protection against inactivation was afforded by anaerobiosis, organic substrates of ammonia mono-oxygenase such as bromoethane, or metal-ion-chelating agents such as thiourea. The presence of 10 mM-NH4+ or 1 mM-hydroxylamine made little difference, whereas hydrazine had a potentiating effect. Illumination of cells also caused a bleaching in the absorption spectrum around 380 nm, along with changes in the cytochrome gamma-band region. Similar effects below 400 nm were obtained when organic substrates and inhibitors of the mono-oxygenase were added to cells in the dark. The copper proteins haemocyanin and tyrosinase have a photosensitive oxygenated state with a near-u.v. absorption band of similar half-width. They also have a sensitivity to chelating agents similar to that of ammonia mono-oxygenase. The experimental results are explained in terms of a three-stage catalytic cycle analogous to that for tyrosinase. In resting cells most of the enzyme is believed to be in an oxygenated (Oxy) form, which absorbs maximally at 378 nm and is photosensitive. In the presence of a substrate, one O atom is inserted into the substrate and the other is reduced to water, leaving the enzyme in an oxidized (Met) state. This is followed by a two-electron reduction of the proposed binuclear copper site to give a reduced (Deoxy) state, which can bind O2 to complete the cycle.

Fractionation of polymethylene chains: An electron crystallographic investigation

1986 ◽  
Vol 44 ◽  
pp. 794-795
Author(s):  
Douglas L. Dorset
Keyword(s):  
Cross Section ◽  
Binary Systems ◽  
Linear Chain ◽  
Pure Component ◽  
Organic Substrates ◽  
Crystallographic Investigation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Sizes ◽  
The Stability

A variety of linear chain materials exist as polydisperse systems which are difficultly purified. The stability of continuous binary solid solutions assume that the Gibbs free energy of the solution is lower than that of either crystal component, a condition which includes such factors as relative molecular sizes and shapes and perhaps the symmetry of the pure component crystal structures.Although extensive studies of n-alkane miscibility have been carried out via powder X-ray diffraction of bulk samples we have begun to examine binary systems as single crystals, taking advantage of the well-known enhanced scattering cross section of matter for electrons and also the favorable projection of a paraffin crystal structure posited by epitaxial crystallization of such samples on organic substrates such as benzoic acid.

Development of High Permeability Core Materials for Embeddable Inductors in Flexible Organic Substrates

2003 ◽  
Vol 769 ◽  
Author(s):  
C. K. Liu ◽  
P. L. Cheng ◽  
S. Y. Y. Leung ◽  
T. W. Law ◽  
D. C. C. Lam
Keyword(s):  
Low Temperature ◽  
Sol Gel ◽  
Circuit Board ◽  
Organic Substrates ◽  
Circuit Boards ◽  
High Permeability ◽  
Electrical Measurements ◽  
Different Temperatures ◽  
Spiral Inductors ◽  
Ceramic Tape

AbstractCapacitors, resistors and inductors are surface mounted components on circuit boards, which occupy up to 70% of the circuit board area. For selected applications, these passives are packaged inside green ceramic tape substrates and sintered at temperatures over 700°C in a co-fired process. These high temperature processes are incompatible with organic substrates, and low temperature processes are needed if passives are to be embedded into organic substrates. A new high permeability dual-phase Nickel Zinc Ferrite (DP NZF) core fabricated using a low temperature sol-gel route was developed for use in embedded inductors in organic substrates. Crystalline NZF powder was added to the sol-gel precursor of NZF. The solution was deposited onto the substrates as thin films and heat-treated at different temperatures. The changes in the microstructures were characterized using XRD and SEM. Results showed that addition of NZF powder induced low temperature transformation of the sol-gel NZF phase to high permeability phase at 250°C, which is approximately 350°C lower than transformation temperature for pure NZF sol gel films. Electrical measurements of DP NZF cored two-layered spiral inductors indicated that the inductance increased by three times compared to inductors without the DP NZF cores. From microstructural observations, the increase is correlated with the changes in microstructural connectivity of the powder phase.

Fe-N-C Artificial Enzyme: Activation of Oxygen for Dehydrogenation and Monoxygenation of Organic Substrates under Mild Condition and Cancer Therapeutic Application

2018 ◽  
Author(s):  
Fei He ◽  
Li Mi ◽  
Yanfei Shen ◽  
Toshiyuki Mori ◽  
Songqin Liu ◽  
...  
Keyword(s):  
Mild Condition ◽  
Enzyme Activation ◽  
Artificial Enzymes ◽  
Organic Substrates ◽  
Artificial Enzyme ◽  
Therapeutic Application ◽  
Highly Efficient ◽  
Activation Of Oxygen

Developing highly efficient artificial enzymes that directly employ O<sub>2</sub> as terminal oxidant has long been pursued but has rarely achieved yet. We report Fe-N-C has unusual enzyme-like activity in both dehydrogenation and monoxygenation of organic substrates with ~100% selectivity by direct using O<sub>2</sub>.

Regime of soil humus rural residential areas organic farming systems

2018 ◽  
Vol 2 (95) ◽  
pp. 78-81
Author(s):  
L.I. Shkarivska
Keyword(s):  
Organic Farming ◽  
Rural Areas ◽  
Humus Content ◽  
Farming Systems ◽  
Farming System ◽  
Organic Substrates ◽  
Residential Areas ◽  
Typical Chernozem ◽  
Podzolic Soils ◽  
Organic Farming System

The changes of the soil’s humus soil within the rural areas are investigated for the organic farming system. The most significant impact of organic agriculture on humus content over 55% was observed on soddy podzolic soils (V>75%), the lowest –7,5% on typical chernozem (V≈16%). Changes in the qualitative composition of humus for the introduction of various types of organic substrates are analyzed.

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