From Resting State to the Steady State: Mechanistic Studies of Ene–Yne Metathesis Promoted by the Hoveyda Complex

2016 ◽  
Vol 138 (16) ◽  
pp. 5380-5391 ◽  
Author(s):  
Justin R. Griffiths ◽  
Jerome B. Keister ◽  
Steven T. Diver
Keyword(s):  
Steady State ◽  
Resting State ◽  
Mechanistic Studies

Hydridosilylamido complexes of Ta and Mo isolobal with Berry's zirconocenes: syntheses, β-Si–H agostic interactions, catalytic hydrosilylation, and insight into mechanism

2016 ◽  
Vol 45 (6) ◽  
pp. 2554-2561 ◽  
Author(s):  
Nicolas A. McLeod ◽  
Lyudmila G. Kuzmina ◽  
Ilia Korobkov ◽  
Judith A. K. Howard ◽  
Georgii I. Nikonov
Keyword(s):  
Resting State ◽  
Mechanistic Studies ◽  
Catalytic Hydrosilylation ◽  
Insight Into

The β-SiH agostic complex (ArN)2Mo{η3-N(tBu)SiMe2–H}H is a pre-catalyst for hydrosilylation of carbonyls. Mechanistic studies revealed a non-hydride mechanism, with the benzoxy complex 8 being the resting state.

Rapid degradation of oxidation resistant nitrophenols by TAML activator and H2O2

2015 ◽  
Vol 5 (3) ◽  
pp. 1775-1782 ◽  
Author(s):  
Soumen Kundu ◽  
Arani Chanda ◽  
Jasper V. K. Thompson ◽  
George Diabes ◽  
Sushil K. Khetan ◽  
...  
Keyword(s):  
Resting State ◽  
Substrate Inhibition ◽  
Mechanistic Studies ◽  
Rapid Degradation ◽  
Reversible Binding ◽  
Oxidation Resistant

TAML and H2O2remove toxic nitrophenol pollutants producing innocuous minerals. Mechanistic studies reveal the substrate inhibition due to the reversible binding of nitrophenolate to iron(iii) of the TAML resting state.

How restful is it with all that noise? Comparison of Interleaved silent steady state (ISSS) and conventional imaging in resting-state fMRI

NeuroImage ◽  
2017 ◽  
Vol 147 ◽  
pp. 726-735 ◽  
Author(s):  
J. Andoh ◽  
M. Ferreira ◽  
I.R. Leppert ◽  
R. Matsushita ◽  
B. Pike ◽  
...  
Keyword(s):  
Steady State ◽  
Resting State ◽  
Resting State Fmri ◽  
Conventional Imaging

scholarly journals Mechanistic studies on tyrosinase-catalysed oxidative decarboxylation of 3,4-dihydroxymandelic acid

1992 ◽  
Vol 281 (2) ◽  
pp. 353-357 ◽  
Author(s):  
M Sugumaran ◽  
H Dali ◽  
V Semensi
Keyword(s):  
Steady State ◽  
Visible Region ◽  
Quinone Methide ◽  
Spectral Studies ◽  
Oxidative Decarboxylation ◽  
Mechanistic Studies ◽  
Enzymic Oxidation ◽  
Steady State Kinetic ◽  
State Kinetic ◽  
Alpha Carbon

Mushroom tyrosinase, which is known to convert a variety of o-diphenols into o-benzoquinones, has been shown to catalyse an unusual oxidative decarboxylation of 3,4-dihydroxymandelic acid to 3,4-dihydroxybenzaldehyde [Sugumaran (1986) Biochemistry 25, 4489-4492]. The mechanism of this reaction was re-investigated. Although visible-region spectral studies of the reaction mixture containing 3,4-dihydroxymandelic acid and tyrosinase failed to generate the spectrum of a quinone product during the steady state of the reaction, both trapping experiments and non-steady-state kinetic experiments provided evidence for the transient formation of unstable 3,4-mandeloquinone in the reaction mixture. The visible-region spectrum of mandeloquinone resembled related quinones and exhibited an absorbance maximum at 394 nm. Since attempts to trap the second intermediate, namely alpha,2-dihydroxy-p-quinone methide, were in vain, mechanistic studies were undertaken to provide evidence for its participation. The decarboxylative quinone methide formation from 3,4-mandeloquinone dictates the retention of a proton on the alpha-carbon atom. Hence, if we replace this proton with deuterium, the resultant 3,4-dihydroxybenzaldehyde should retain the deuterium present in the original substrate. To test this hypothesis, we chemoenzymically synthesized alpha-deuterated 3,4-dihydroxymandelic acid and examined its enzymic oxidation. Our studies reveal that the resultant 3,4-dihydroxybenzaldehyde retained nearly 90% of the deuterium, strongly indicating the transient formation of quinone methide. On the basis of these findings it is concluded that the enzymic oxidation of 3,4-dihydroxymandelic acid generates the conventional quinone product, which, owing to its unstability, is rapidly decarboxylated to generate transient alpha,2-dihydroxy-p-quinone methide. The coupled dienone-phenol re-arrangement and keto-enol tautomerism of this quinone methide produce the observed 3,4-dihydroxybenzaldehyde.

Metabolic depression and enhanced O2 affinity of mitochondria in hypoxic hypometabolism

2000 ◽  
Vol 279 (4) ◽  
pp. R1205-R1214 ◽  
Author(s):  
Julie St-Pierre ◽  
Glenn J. Tattersall ◽  
Robert G. Boutilier
Keyword(s):  
Skeletal Muscle ◽  
Steady State ◽  
Resting State ◽  
Rana Temporaria ◽  
Active State ◽  
Metabolic Depression ◽  
Biological Organization ◽  
Isolated Mitochondria ◽  
Respiration Rates ◽  
Hypoxic Water

This study examined whether the steady-state hypometabolism seen in overwintering frogs ( Rana temporaria) is reflected at the mitochondrial level either by a reduction in their resting (state 4) and active (state 3) respiration rates and/or by increases in O2 affinity. We isolated mitochondria from the skeletal muscle of cold-submerged frogs at different stages during their hibernation in normoxic and hypoxic water. A modest metabolic depression at the whole animal level (normoxic submergence) was not associated with a reduction in mitochondrial state 4 and state 3 respiration rates. However, mitochondria isolated from frogs that were submerged for 1 mo manifested an increase in their O2 affinity compared with controls and with animals submerged for 4 mo. Hypometabolism was more pronounced at the whole animal level during hypoxic submergence and was accompanied by 1) a reduction in mitochondrial state 4 and state 3 rates and 2) an increase in the O2affinity of mitochondria. These findings demonstrate that metabolic depression can be reflected at all levels of biological organization in hypoxia-tolerant animals.

Catalytic Hydrogenation of Unsaturated Carboxylic Adds Using N,N-Dimethylacetamide Solutions of Ruthenium(I) Chlorides

1974 ◽  
Vol 52 (22) ◽  
pp. 3760-3768 ◽  
Author(s):  
Benjamin C. Hui ◽  
Brian R. James
Keyword(s):  
Steady State ◽  
Fumaric Acid ◽  
Mechanistic Studies ◽  
Steady State Concentration ◽  
Hydrogen Addition ◽  
Mild Conditions ◽  
Unsaturated Carboxylic Acids ◽  
Hydrogen Atom Transfers ◽  
State Concentration ◽  
Hydrogenation Of Ethylene

N,N-Dimethylacetamide solutions of dimeric ruthenium(I) chlorides catalyze homogeneously the hydrogenation of ethylene and unsaturated carboxylic acids under mild conditions. Kinetic and mechanistic studies show that the catalysis involves a monomeric Ru(I) complex which forms reversibly a steady state concentration of a Ru(III)H2 species; this reacts with olefinic substrate to yield saturated product by two successive single hydrogen atom transfers with regeneration of the Ru(I) catalyst. The overall hydrogen addition to fumaric acid is cis. Hydrogenation of maleic acid is accompanied by an efficient isomerization to fumaric acid.

scholarly journals Resting-State fMRI Using Passband Balanced Steady-State Free Precession

PLoS ONE ◽  
2014 ◽  
Vol 9 (3) ◽  
pp. e91075 ◽  
Author(s):  
Joe S. Cheng ◽  
Patrick P. Gao ◽  
Iris Y. Zhou ◽  
Russell W. Chan ◽  
Queenie Chan ◽  
...  
Keyword(s):  
Steady State ◽  
Resting State ◽  
Steady State Free Precession ◽  
Resting State Fmri ◽  
Free Precession
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