Revealing Ultrafast Two-Electron Transfer Over Tryptophan with Mass Spectrometry

Electron transfer crucial to bioenergetics is ubiquitously present in biological systems but most of them escape from direct observations. By using tryptophan and its derivatives with 1-CH3, 2-CH3, 5-CH3 and 5-OH substitutions as model molecules, we have unambiguously demonstrated successive two-electron transfer to tryptophan as well as electronic and vibrational excited molecular dissociation with mass spectrometry. The ultra-short time delay between two electrons down to sub-attosecond over a distance less than 10 Å was found to cause the strong coupling of electronic and vibrational excitations that was validated by the observation of radical-radical coupling. Intramolecular H migrations along with two-electron transfer was demonstrated with H/D exchange and 13C stable isotope labeling. This proposed technique allows us to observe the ultrafast electron transfer from tryptophan to the heme group in myoglobin proteins. It bridges electron transfer to energy transfer that has been revealed in FRET alone. FeII (porph•‐) and FeI (porph•‐) resulting from one- and two-electron transfer, respectively, have been unambiguously identified

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A structure–guided screening strategy for the discovery and identification of potential gibberellins from plant samples using liquid chromatography–mass spectrometry assisted by chemical isotope labeling

Analytica Chimica Acta ◽

10.1016/j.aca.2021.338505 ◽

2021 ◽

Vol 1163 ◽

pp. 338505

Author(s):

Wen-Jing Cai ◽

Chen Zeng ◽

Xiao-Yun Zhang ◽

Tiantian Ye ◽

Yu-Qi Feng

Keyword(s):

Mass Spectrometry ◽

Liquid Chromatography ◽

Isotope Labeling ◽

Screening Strategy ◽

Liquid Chromatography Mass Spectrometry ◽

Chromatography Mass Spectrometry ◽

Plant Samples ◽

Chemical Isotope Labeling

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Rhinovirus prevalence as indicator for efficacy of measures against SARS-CoV-2

BMC Public Health ◽

10.1186/s12889-021-11178-w ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Simo Kitanovski ◽

Gibran Horemheb-Rubio ◽

Ortwin Adams ◽

Barbara Gärtner ◽

Thomas Lengauer ◽

...

Keyword(s):

Respiratory Viruses ◽

Emerging Viruses ◽

Prevalence Data ◽

Incidence Data ◽

Bayes Inference ◽

Current Prevalence ◽

Highest Density Interval ◽

Short Time ◽

Short Time Delay ◽

Better Than

Abstract Background Non-pharmaceutical measures to control the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) should be carefully tuned as they can impose a heavy social and economic burden. To quantify and possibly tune the efficacy of these anti-SARS-CoV-2 measures, we have devised indicators based on the abundant historic and current prevalence data from other respiratory viruses. Methods We obtained incidence data of 17 respiratory viruses from hospitalized patients and outpatients collected by 37 clinics and laboratories between 2010-2020 in Germany. With a probabilistic model for Bayes inference we quantified prevalence changes of the different viruses between months in the pre-pandemic period 2010-2019 and the corresponding months in 2020, the year of the pandemic with noninvasive measures of various degrees of stringency. Results We discovered remarkable reductions δ in rhinovirus (RV) prevalence by about 25% (95% highest density interval (HDI) [−0.35,−0.15]) in the months after the measures against SARS-CoV-2 were introduced in Germany. In the months after the measures began to ease, RV prevalence increased to low pre-pandemic levels, e.g. in August 2020 δ=−0.14 (95% HDI [−0.28,0.12]). Conclusions RV prevalence is negatively correlated with the stringency of anti-SARS-CoV-2 measures with only a short time delay. This result suggests that RV prevalence could possibly be an indicator for the efficiency for these measures. As RV is ubiquitous at higher prevalence than SARS-CoV-2 or other emerging respiratory viruses, it could reflect the efficacy of noninvasive measures better than such emerging viruses themselves with their unevenly spreading clusters.

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Suppression of runaway electron generation by massive helium injection after induced disruptions on TEXTOR

Journal of Plasma Physics ◽

10.1017/s0022377815001051 ◽

2015 ◽

Vol 81 (5) ◽

Cited By ~ 5

Author(s):

A. Lvovskiy ◽

H. R. Koslowski ◽

L. Zeng ◽

Keyword(s):

Time Delay ◽

Runaway Electron ◽

Critical Density ◽

Runaway Electrons ◽

Electron Generation ◽

Disruption Mitigation ◽

Order Of Magnitude ◽

Short Time ◽

Short Time Delay

Disruptions with runaway electron generation have been deliberately induced by injection of argon using a disruption mitigation valve. A second disruption mitigation valve has been utilised to inject varying amounts of helium after a short time delay. No generation of runaway electrons has been observed when more than a critical amount of helium has been injected no later than 5 ms after the triggering of the first valve. The required amount of helium for suppression of runaway electron generation is up to one order of magnitude lower than the critical density according to Connor & Hastie (1975) and Rosenbluth & Putvinski (1997).

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Rapid intra-adrenal feedback regulation of glucocorticoid synthesis

Journal of The Royal Society Interface ◽

10.1098/rsif.2014.0875 ◽

2015 ◽

Vol 12 (102) ◽

pp. 20140875 ◽

Cited By ~ 32

Author(s):

J. J. Walker ◽

F. Spiga ◽

R. Gupta ◽

Z. Zhao ◽

S. L. Lightman ◽

...

Keyword(s):

Adrenal Glands ◽

Feedback Regulation ◽

Feedback Mechanism ◽

Acth Secretion ◽

Primary Mechanism ◽

Acth Receptor ◽

Local Feedback ◽

Short Time ◽

Pituitary Adrenal Axis ◽

Short Time Delay

The hypothalamic–pituitary–adrenal axis is a vital neuroendocrine system that regulates the secretion of glucocorticoid hormones from the adrenal glands. This system is characterized by a dynamic ultradian hormonal oscillation, and in addition is highly responsive to stressful stimuli. We have recently shown that a primary mechanism generating this ultradian rhythm is a systems-level interaction where adrenocorticotrophin hormone (ACTH) released from the pituitary stimulates the secretion of adrenal glucocorticoids, which in turn feedback at the level of the pituitary to rapidly inhibit ACTH secretion. In this study, we combine experimental physiology and mathematical modelling to investigate intra-adrenal mechanisms regulating glucocorticoid synthesis. Our modelling results suggest that glucocorticoids can inhibit their own synthesis through a very rapid (within minutes), presumably non-genomic, intra-adrenal pathway. We present further evidence for the existence of a short time delay in this intra-adrenal inhibition, and also that at the initiation of each ACTH stimulus, this local feedback mechanism is rapidly antagonized, presumably via activation of the specific ACTH receptor (MC2R) signalling pathway. This mechanism of intra-adrenal inhibition enables the gland to rapidly release glucocorticoids while at the same time preventing uncontrolled release of glucocorticoids in response to large surges in ACTH associated with stress.

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Studies on electrooxidation of lignin and lignin model compounds. Part 1: Direct electrooxidation of non-phenolic lignin model compounds

Holzforschung ◽

10.1515/hf.2011.069 ◽

2012 ◽

Vol 66 (3) ◽

Cited By ~ 1

Author(s):

Takumi Shiraishi ◽

Toshiyuki Takano ◽

Hiroshi Kamitakahara ◽

Fumiaki Nakatsubo

Keyword(s):

Electron Transfer ◽

Cyclic Voltammetry ◽

Carbonyl Compounds ◽

Model Compounds ◽

Lignin Model Compounds ◽

Bulk Electrolysis ◽

Lignin Model ◽

Dimeric Compound ◽

High Yields ◽

Short Time

Abstract The direct anodic oxidation of non-phenolic lignin model compounds was investigated to understand their basic behaviors. The results of cyclic voltammetry (CV) studies of monomeric model, such as 1-(4-ethoxy-3-methoxyphenyl)ethanol, are interpreted as the oxidation for Cα-carbonylation did not proceed in the reaction without a catalyst, but a base promotes this reaction. Indeed, the bulk electrolyses of the monomeric lignin model compounds with 2,6-lutidine afforded the corresponding Cα-carbonyl compounds in high yields (60–80%). It is suggested that deprotonation at Cα-H in the ECEC mechanism (E=electron transfer and C=chemical step) is important for Cα-carbonylation. In the uncatalyzed bulk electrolysis of a β-O-4 model dimeric compound, 4-ethoxy-3-methoxyphenylglycerol-β-guaiacyl ether, the corresponding Cα-carbonyl compound was not detected but as a result of Cα-Cβcleavage 4-O-ethylvanillin was found in 40% yield. In the electrolysis reaction in the presence of 2,6-lutidine (as a sterically hindered light base), the reaction stopped for a short time unexpectedly. These results indicate the different electrochemical behavior of simple monomeric model compounds and dimeric β-O-4 models. The conclusion is that direct electrooxidation is unsuitable for Cα-carbonylation of lignin.

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