scholarly journals Ferryl haem protonation gates peroxidatic reactivity in globins

2007 ◽  
Vol 403 (3) ◽  
pp. 391-395 ◽  
Author(s):  
Radu Silaghi-Dumitrescu ◽  
Brandon J. Reeder ◽  
Peter Nicholls ◽  
Chris E. Cooper ◽  
Michael T. Wilson
Keyword(s):  
Subarachnoid Haemorrhage ◽  
Optical Transition ◽  
Chemical Mechanism ◽  
Stopped Flow ◽  
Rapid Scan ◽  
Ferryl Species ◽  
First Time

Ferryl (Fe(IV)=O) species are involved in key enzymatic processes with direct biomedical relevance; among others, the uncontrolled reactivities of ferryl Mb (myoglobin) and Hb (haemoglobin) have been reported to be central to the pathology of rhabdomyolysis and subarachnoid haemorrhage. Rapid-scan stopped-flow methods have been used to monitor the spectra of the ferryl species in Mb and Hb as a function of pH. The ferryl forms of both proteins display an optical transition with pK∼4.7, and this is assigned to protonation of the ferryl species itself. We also demonstrate for the first time a direct correlation between Hb/Mb ferryl reactivity and ferryl protonation status, simultaneously informing on chemical mechanism and toxicity and with broader biochemical implications.

Optical Properties and New Functionality of Nanocrystalline CuCl and Ge

1992 ◽  
Vol 283 ◽  
Author(s):  
Yasuaki Masumoto
Keyword(s):  
Optical Transition ◽  
Optical Gain ◽  
Glassy Matrix ◽  
Bulk Crystals ◽  
Electron Microscopic ◽  
Visible Photoluminescence ◽  
Resolution Electron ◽  
Microscopic Studies ◽  
Direct Optical Transition ◽  
First Time

ABSTRACTLasing of nanocrystalline CuCl embedded in a NaCl single crystal wasobserved for the first time. Lasing takes place at 77 K in nanocrystalline CuCl sandwiched between dielectric mirrors under the pulsed ultraviolet laser excitation. The lasing transition is that from bi-exciton to exciton. The lasing is observed up to 108 K. The optical gain of nanocrystalline CuCl is almost the same as that of bulk crystals in spite of the low concentration of CuCl in the NaCl matrix.The origin of visible photoluminescence of nanocrystalline Ge in SiO2 glassy matrix has been studied. Spectroscopic analyses of nanocrystalline Ge indicate that the room-temperature photoluminescence comes from nanocrystalline Ge of diameter of 4 nm or less. High-resolution electron microscopic studies imply that the structure of nanocrystalline Ge of diameter ≤ 4 nm differs from the diamond structure. These data suggest that new nanostructure crystalline Ge having a character of direct optical transition exhibits the visible photoluminescence.

scholarly journals Особенности морфологии и оптических свойств наноструктур дисульфида молибдена от мономолекулярного слоя до фрактолообразной субструктуры

2019 ◽  
Vol 53 (7) ◽  
pp. 940
Author(s):  
Э.П. Домашевская ◽  
Д.Л. Голощапов ◽  
Аль Хайлани Хасан Исмаил Дамбос ◽  
Е.В. Руднев ◽  
М.В. Гречкина ◽  
...  
Keyword(s):  
Room Temperature ◽  
Optical Transition ◽  
Optical Absorption Spectroscopy ◽  
Molybdenum Metal ◽  
Force Microscopy ◽  
Atomic Force ◽  
Monomolecular Layers ◽  
First Time ◽  
Different Thickness ◽  
Hot Zone

Abstract. The aim of the work is to show the effect of layer thickness on the features of the morphology and optical properties of MoS2 nanostructures, including the monomolecular layers, formed during the gas transporting transfer of sulfur vapors to the reactor hot zone with a molybdenum metal and subsequent deposition on the mica (muscavite) substrates. The results of the atomic force microscopy, optical absorption spectroscopy and Raman spectroscopy of molybdenum disulfide nanostructures of different thickness, obtained in temperatures interval of gas transport synthesis 525-600°C, show that a monomolecular MoS2 layers, containing trigonal domains and having a width of the band gap 1.84 eV at a direct-gap optical transition with the formation of excitons at room temperature, can be obtained. For the first time, fractal-like substructures were obtained, in the Raman spectra of which the values of the modes of intralayer and interlayer oscillations E12g 377.5 cm-1 and A1g 403.8 differ not only from the corresponding values of the modes of the monomolecular layer, but also from the known values of bulk samples. The frequency of the intralayer mode in these samples, E12g 377.5 cm-1, is the smallest of all known values.

Kinetics of the Formation of the Blue Complex CrO(O 2 ) 2 Formed by Dichromate and H 2 O 2 in Acid Solutions. A Stopped-Flow Investigation Using Rapid-Scan UV-VIS Detection

2002 ◽  
Vol 133 (10) ◽  
pp. 1363-1372 ◽  
Author(s):  
Günter Grampp ◽  
Stephan Landgraf ◽  
Tomasz Wesierski ◽  
Beata Jankowska ◽  
Ewa Kalisz ◽  
...  
Keyword(s):  
Stopped Flow ◽  
Acid Solutions ◽  
Rapid Scan ◽  
Flow Investigation ◽  
Kinetics Of

A role for cofilin in the activation of store-operated calcium entry by de novo conformational coupling in human platelets

Blood ◽  
2006 ◽  
Vol 107 (3) ◽  
pp. 973-979 ◽  
Author(s):  
Pedro C. Redondo ◽  
Matthew T. Harper ◽  
Juan A. Rosado ◽  
Stewart O. Sage
Keyword(s):  
De Novo ◽  
Human Platelets ◽  
Stopped Flow ◽  
Actin Remodeling ◽  
Major Mechanism ◽  
Initial Decrease ◽  
Store Operated Calcium Entry ◽  
Conformational Coupling ◽  
Time Changes ◽  
First Time

AbstractStore-operated Ca2+ entry (SOCE) is a major mechanism for Ca2+ influx in platelets and other cells. De novo conformational coupling between elements in the plasma membrane and Ca2+ stores, where the actin cytoskeleton plays an important regulatory role, has been proposed as the most likely mechanism to activate SOCE in platelets. Here we have examined for the first time changes in platelet F-actin levels on a subsecond time scale. Using stopped-flow fluorimetry and a quenched-flow approach, we provide evidence for the involvement of cofilin in actin filament reorganization and SOCE in platelets. Thrombin (0.1 U/mL) evoked an initial decrease in F-actin that commenced within 0.1 second and reached a minimum 0.9 second after stimulation, prior to the activation of SOCE. F-actin then increased, exceeding basal levels approximately 2.5 seconds after stimulation. Thrombin also induced cofilin dephosphorylation and activation, which paralleled the changes observed in F-actin, and rapid Btk activation. Inhibition of cofilin dephosphorylation by LFM-A13 resulted in the loss of net actin depolymerization and an increased delay in SOCE initiation. These results suggest that cofilin is important for the rapid actin remodeling necessary for the activation of SOCE in platelets through de novo conformational coupling.

ChemInform Abstract: Stopped-Flow and Rapid-Scan Spectral Examination of the Iron(III)

1986 ◽  
Vol 17 (11) ◽  
Author(s):  
M. BIRUS ◽  
Z. BRADIC ◽  
N. KUJUNDZIC ◽  
M. PRIBANIC ◽  
P. C. WILKINS ◽  
...  
Keyword(s):  
Stopped Flow ◽  
Rapid Scan
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