Metal Insertion into the Open Face of anisonido-Metallathiaborane Cluster:  Formation and Characterization of [2-PPh3-2,3-Cl2-2,3-(μ-Cl)-3,7-(μ-dppm)-closo-2,3,1-Rh2SB9H8] from [1-PPh3-{1,3-(μ-dppm)}-isonido-1,2-RhSB9H8]

2003 ◽  
Vol 22 (13) ◽  
pp. 2548-2550 ◽  
Author(s):  
Oleg Volkov ◽  
Nigam P. Rath ◽  
Lawrence Barton
Keyword(s):  
Cluster Formation ◽  
Metal Insertion ◽  
Open Face

Purification and characterization of ferro- and cobalto-chelatases

1988 ◽  
Vol 66 (1) ◽  
pp. 32-39 ◽  
Author(s):  
Eduardo T. Cánepa ◽  
Elena B.C. Llambías
Keyword(s):  
Molecular Weight ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Purification And Characterization ◽  
Degree Of Unsaturation ◽  
Apparent Homogeneity ◽  
Optimum Ph ◽  
Single Protein ◽  
Metal Insertion

Pig liver ferrochelatase was purified 465-fold with about 30% yield, to apparent homogeneity, by a procedure involving solubilization from mitochondria, ammonium sulfate fractionation, and Sephacryl S-300 chromatography. The fraction of each purification step had cobaltochelatase as well as ferrochelatase activity. A purified protein of molecular weight 40 000 was found by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. A molecular weight of approximately 240 000 was obtained by Sephacryl S-300 chromatography. Both activities of the purified fraction increased linearly with time until 2 h. but nonlinear plots were obtained with increasing concentrations of protein. Their optimum pH values were similar. Km values were, for ferrochelatase activity, 23.3 μM for the metal and 30.3 μM for mesoporphyrin. and for cobaltochelatase activity. 27 and 45.5 μM, respectively. Fe2+ and Co2+ each protected against inactivation by heat. Pb2+, Zn2+, Cu2+, or Hg2+ inhibited both activities, while Mn2+ slightly activated; Mg2+ had no effect, at the concentrations tested. There appeared to be an involvement of sulfhydryl groups in metal insertion. Lipids, in correlation with their degree of unsaturation, activated both purified activities; phospholipids also had activation effects. We conclude that a single protein catalyzes the insertion of Fe2+ or Co2+ into mesoporphyrin.

scholarly journals Point Defect Cluster Formation in Iron Displacement Cascades UP to 50 keV

1998 ◽  
Vol 540 ◽  
Author(s):  
Roger E. Stoller
Keyword(s):  
Cluster Formation ◽  
Significant Degree ◽  
Defect Cluster ◽  
Size Distributions ◽  
Vacancy Clusters ◽  
Cascade Energy ◽  
Vacancy Site ◽  
Iron Based ◽  
Property Changes

AbstractThe results of molecular dynamics displacement cascade simulations in iron at energies up to 50 keV and temperatures of 100, 600, and 900K are summarized, with a focus on the characterization of interstitial and vacancy clusters that are formed directly within the cascade. The fraction of the surviving point defects contained in clusters, and the size distributions of these in-cascade clusters have been determined. Although the formation of true vacancy clusters appears to be inhibited in iron, a significant degree of vacancy site correlation was observed. These well correlated arrangements of vacancies can be considered nascent clusters, and they have been observed to coalesce during longer term Monte Carlo simulations which permit short range vacancy diffusion. Extensive interstitial clustering was observed. The temperature and cascade energy dependence of the cluster size distributions are discussed in terms of their relevance to microstructural evolution and mechanical property changes in irradiated iron-based alloys.

scholarly journals Characterization of Multiphase Polypyrrole/Vanadium Oxide Nano Composites for a.c. Conductivity and Dielectric Properties

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Nihal B Kottan ◽  
Prajwal M Laxmeesha ◽  
Purnachandra Ganesh K M ◽  
Chaluvaraju BV ◽  
Murugendrappa M V
Keyword(s):  
Vanadium Oxide ◽  
Phase 1 ◽  
Cluster Formation ◽  
Oxide Phase ◽  
Nano Composites ◽  
Phase 2 ◽  
Hydrothermal Technique ◽  
Oxidation Method ◽  
Exponential Increase

Vanadium oxide: Phase-1 and Phase-2 nano powers were synthesized from vanadium pentoxide in the presence of glucose using hydrothermal technique. The polypyrrole/vanadium oxide (PV P-1 and PV P-2) nano composites were synthesized with 15, 30, 45 and 60 weight percents of vanadium oxide: Phase-1 and Phase-2 in pyrrole, by the chemical polymerization (oxidation) method. The SEM micrographs of vanadium oxide: Phase-1 and Phase-2 nano powders have shown  mixture of nano belts & rods and PV P-1 & PV P-2 nano composites indicate that the composites have cluster formation with almost spherical nature particles and form elongated chains at some places. Conductivity versus frequency  plots shown that exponential increase for conductivity. The value of s increases to 1.13x10-3 S/cm for 15 wt. % of VO2 P-1 in polypyrrole & to 2.43x10-3 S/cm for 30 wt. % of VO2 P-2 in polypyrrole at 1 MHz.

Characterization of Au nano-cluster formation on and diffusion in polystyrene using XPS peak shape analysis

2007 ◽  
Vol 601 (15) ◽  
pp. 3261-3267 ◽  
Author(s):  
Shaaker Hajati ◽  
Vladimir Zaporojtchenko ◽  
Franz Faupel ◽  
Sven Tougaard
Keyword(s):  
Shape Analysis ◽  
Cluster Formation ◽  
Peak Shape ◽  
Nano Cluster ◽  
And Diffusion

Characterization of the NifU and NifS Fe−S Cluster Formation Proteins Essential for Viability inHelicobacter pylori†

Biochemistry ◽  
2000 ◽  
Vol 39 (51) ◽  
pp. 16213-16219 ◽  
Author(s):  
Jonathan W. Olson ◽  
Jeffery N. Agar ◽  
Michael K. Johnson ◽  
Robert J. Maier
Keyword(s):  
Cluster Formation

scholarly journals Fundamental characterization of wheat gluten

2021 ◽  
Author(s):  
Marina Schopf ◽  
Monika Christine Wehrli ◽  
Thomas Becker ◽  
Mario Jekle ◽  
Katharina Anne Scherf
Keyword(s):  
Crude Protein ◽  
Cluster Formation ◽  
Wheat Gluten ◽  
Protein Composition ◽  
Spectroscopic Properties ◽  
Absorption Capacity ◽  
Wheat Starch ◽  
Score Plot ◽  
Vital Wheat Gluten

AbstractVital wheat gluten plays an important role in the food industry, especially in baking to help standardize dough properties and improve bread volume. However, a fundamental characterization of a wide variety of vital gluten samples is not available so far. This would be necessary to relate compositional characteristics to the production process. Therefore, we analyzed the content of crude protein, starch, lipids and ash, oil and water absorption capacity, particle size distribution, gluten protein composition and spectroscopic properties of 39 vital gluten samples from 6 different suppliers. Principle component analysis of all analytical parameters revealed that the samples from one specialized vital gluten manufacturer had a different composition and a greater variability compared to all other samples from wheat starch producers. While the composition of vital gluten samples from the same manufacturer was similar and the score plot showed a cluster formation for samples from three suppliers, the variability over all samples was comparatively low. The samples from the other suppliers were too similar altogether so that it was hardly possible to identify clear differences, also related to functionality.

Understanding how small helical proteins fold: conformational dynamics of Im proteins relevant to their folding landscapes

2012 ◽  
Vol 40 (2) ◽  
pp. 424-428 ◽  
Author(s):  
Angelo Miguel Figueiredo ◽  
Geoffrey R. Moore ◽  
Sara B.-M. Whittaker
Keyword(s):  
Cluster Formation ◽  
Conformational Dynamics ◽  
Unfolded Protein ◽  
Folding Rates ◽  
Small Proteins ◽  
Helical Proteins ◽  
Partially Unfolded ◽  
Hydrophobic Helix ◽  
Partially Unfolded States

Understanding the mechanism of folding of small proteins requires characterization of their starting unfolded states and any partially unfolded states populated during folding. Here, we review what is known from NMR about these states of Im7, a 4-helix bundle protein that folds via an on-pathway intermediate, and show that there is an alignment of non-native structure in urea-unfolded Im7 with the helices of native Im7 that is a consequence of hydrophobic helix-promoting residues also promoting cluster-formation in the unfolded protein. We suggest that this kind of alignment is present in other proteins and is relevant to how native state topology determines folding rates.

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