Prospects of Combating Arsenic: Physico-chemical Aspects

2017 ◽  
pp. 103-121 ◽  
Author(s):  
Soumya Chatterjee ◽  
Mridul Chetia ◽  
Anna Voronina ◽  
Dharmendra K. Gupta
Keyword(s):  
Physico Chemical

Decoration of specific sites on freeze-fractured membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 140-141
Author(s):  
H. Gross ◽  
H. Moor
Keyword(s):  
Pure Water ◽  
Freeze Fracture ◽  
Chemical Properties ◽  
Surface Forces ◽  
Sulfate Pentahydrate ◽  
Copper Sulfate Pentahydrate ◽  
Physico Chemical ◽  
Water Of Hydration ◽  
Small Container ◽  
Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

Activation of cytochrome c to a peroxidase compound I-type intermediate by H2O2: relevance to redox signalling in apoptosis

2004 ◽  
Vol 71 ◽  
pp. 97-106 ◽  
Author(s):  
Mark Burkitt ◽  
Clare Jones ◽  
Andrew Lawrence ◽  
Peter Wardman
Keyword(s):  
Cytochrome C ◽  
Hydroxyl Radical ◽  
Redox Regulation ◽  
Chemotherapeutic Agents ◽  
Tyrosyl Radical ◽  
Compound I ◽  
Definitive Evidence ◽  
Enhanced Production ◽  
Physico Chemical

The release of cytochrome c from mitochondria during apoptosis results in the enhanced production of superoxide radicals, which are converted to H2O2 by Mn-superoxide dismutase. We have been concerned with the role of cytochrome c/H2O2 in the induction of oxidative stress during apoptosis. Our initial studies showed that cytochrome c is a potent catalyst of 2′,7′-dichlorofluorescin oxidation, thereby explaining the increased rate of production of the fluorophore 2′,7′-dichlorofluorescein in apoptotic cells. Although it has been speculated that the oxidizing species may be a ferryl-haem intermediate, no definitive evidence for the formation of such a species has been reported. Alternatively, it is possible that the hydroxyl radical may be generated, as seen in the reaction of certain iron chelates with H2O2. By examining the effects of radical scavengers on 2′,7′-dichlorofluorescin oxidation by cytochrome c/H2O2, together with complementary EPR studies, we have demonstrated that the hydroxyl radical is not generated. Our findings point, instead, to the formation of a peroxidase compound I species, with one oxidizing equivalent present as an oxo-ferryl haem intermediate and the other as the tyrosyl radical identified by Barr and colleagues [Barr, Gunther, Deterding, Tomer and Mason (1996) J. Biol. Chem. 271, 15498-15503]. Studies with spin traps indicated that the oxo-ferryl haem is the active oxidant. These findings provide a physico-chemical basis for the redox changes that occur during apoptosis. Excessive changes (possibly catalysed by cytochrome c) may have implications for the redox regulation of cell death, including the sensitivity of tumour cells to chemotherapeutic agents.

Freeze-Dried Matrices for Buccal Administration of Propranolol in Children: Physico-Chemical and Functional Characterization

2020 ◽  
Author(s):  
Angela Abruzzo ◽  
Alessandra Crispini ◽  
Cecilia Prata ◽  
Rosanna Adduci ◽  
Fiore Pasquale Nicoletta ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Physico Chemical ◽  
Freeze Dried

PHYSICO CHEMICAL PROPERTIES OF NICKEL OXIDE AT HIGH TEMPERATURE

1976 ◽  
Vol 37 (C7) ◽  
pp. C7-438-C7-442 ◽  
Author(s):  
R. FARHI ◽  
G. PETOT-ERVAS
Keyword(s):  
High Temperature ◽  
Nickel Oxide ◽  
Chemical Properties ◽  
Physico Chemical

Physico-Chemical Properties of Recombinant Desulphatohirudin

1990 ◽  
Vol 63 (03) ◽  
pp. 499-504 ◽  
Author(s):  
A Electricwala ◽  
L Irons ◽  
R Wait ◽  
R J G Carr ◽  
R J Ling ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Gel Filtration ◽  
Chemical Properties ◽  
Alpha Helix ◽  
Apparent Molecular Weight ◽  
Correlation Spectroscopy ◽  
Nmr Studies ◽  
Recombinant Hirudin ◽  
Physico Chemical ◽  
Recombinant Molecule

SummaryPhysico-chemical properties of recombinant desulphatohirudin expressed in yeast (CIBA GEIGY code No. CGP 39393) were reinvestigated. As previously reported for natural hirudin, the recombinant molecule exhibited abnormal behaviour by gel filtration with an apparent molecular weight greater than that based on the primary structure. However, molecular weight estimation by SDS gel electrophoresis, FAB-mass spectrometry and Photon Correlation Spectroscopy were in agreement with the theoretical molecular weight, with little suggestion of dimer or aggregate formation. Circular dichroism studies of the recombinant molecule show similar spectra at different pH values but are markedly different from that reported by Konno et al. (13) for a natural hirudin-variant. Our CD studies indicate the presence of about 60% beta sheet and the absence of alpha helix in the secondary structure of recombinant hirudin, in agreement with the conformation determined by NMR studies (17)

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