On the controversy of metal ion composition on amine oxygenase (AurF): a computational investigation

2012 ◽  
Vol 14 (25) ◽  
pp. 9050 ◽  
Author(s):  
Prabha Jayapal ◽  
Gopalan Rajaraman
Keyword(s):  
Metal Ion ◽  
Ion Composition ◽  
Computational Investigation

scholarly journals Factors That Affect the Enlargement of Bacterial Protoplasts and Spheroplasts

2020 ◽  
Vol 21 (19) ◽  
pp. 7131
Author(s):  
Hiromi Nishida
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Bacterial Cell ◽  
Metal Ion ◽  
Bacterial Species ◽  
Bacterial Cells ◽  
Cell Enlargement ◽  
Ion Composition ◽  
Gene Manipulation ◽  
Peptidoglycan Biosynthesis

Cell enlargement is essential for the microinjection of various substances into bacterial cells. The cell wall (peptidoglycan) inhibits cell enlargement. Thus, bacterial protoplasts/spheroplasts are used for enlargement because they lack cell wall. Though bacterial species that are capable of gene manipulation are limited, procedure for bacterial cell enlargement does not involve any gene manipulation technique. In order to prevent cell wall resynthesis during enlargement of protoplasts/spheroplasts, incubation media are supplemented with inhibitors of peptidoglycan biosynthesis such as penicillin. Moreover, metal ion composition in the incubation medium affects the properties of the plasma membrane. Therefore, in order to generate enlarged cells that are suitable for microinjection, metal ion composition in the medium should be considered. Experiment of bacterial protoplast or spheroplast enlargement is useful for studies on bacterial plasma membrane biosynthesis. In this paper, we have summarized the factors that influence bacterial cell enlargement.

Constituents of unionid extrapallial fluid. ii ph and metal ion composition

Hydrobiologia ◽  
1976 ◽  
Vol 50 (1) ◽  
pp. 89-93 ◽  
Author(s):  
James E. Pietrzak ◽  
John M. Bates ◽  
Ronald M. Scott
Keyword(s):  
Metal Ion ◽  
Ion Composition ◽  
Extrapallial Fluid

scholarly journals Regulation of the Bacillus subtilis fur and perR Genes by PerR: Not All Members of the PerR Regulon Are Peroxide Inducible

2002 ◽  
Vol 184 (12) ◽  
pp. 3276-3286 ◽  
Author(s):  
Mayuree Fuangthong ◽  
Andrew F. Herbig ◽  
Nada Bsat ◽  
John D. Helmann
Keyword(s):  
Hydrogen Peroxide ◽  
Bacillus Subtilis ◽  
Metal Ion ◽  
Target Genes ◽  
Regulatory Region ◽  
Transcriptional Response ◽  
Ion Composition ◽  
Genetic Studies ◽  
Cellular Metal

ABSTRACT PerR is a ferric uptake repressor (Fur) homolog that functions as the central regulator of the inducible peroxide stress response in Bacillus subtilis. PerR has been previously demonstrated to regulate the mrgA, katA, ahpCF, hemAXCDBL, and zosA genes. We now demonstrate that PerR also mediates both the repression of its own gene and that of fur. Whereas PerR-mediated repression of most target genes can be elicited by either manganese or iron, repression of perR and fur is selective for manganese. Genetic studies indicate that repression of PerR regulon genes by either manganese or iron requires PerR and is generally independent of Fur. Indeed, in a fur mutant, iron-mediated repression is enhanced. Unexpectedly, repression of the fur gene by manganese appears to require both PerR and Fur, but only PerR binds to the fur regulatory region in vitro. The fur mutation appears to act indirectly by affecting cellular metal ion pools and thereby affecting PerR-mediated repression. While many components of the perR regulon are strongly induced by hydrogen peroxide, little, if any, induction of fur and perR could be demonstrated. Thus, not all components of the PerR regulon are components of the peroxide stimulon. We suggest that PerR exists in distinct metallated forms that differ in DNA target selectivity and in sensitivity to oxidation. This model is supported by the observation that the metal ion composition of the growth medium can greatly influence the transcriptional response of the various PerR regulon genes to hydrogen peroxide.

scholarly journals The organophosphate-degrading enzyme from Agrobacterium radiobacter displays mechanistic flexibility for catalysis

2010 ◽  
Vol 432 (3) ◽  
pp. 565-573 ◽  
Author(s):  
Fernanda Ely ◽  
Kieran S. Hadler ◽  
Lawrence R. Gahan ◽  
Luke W. Guddat ◽  
David L. Ollis ◽  
...  
Keyword(s):  
Metal Ion ◽  
Binding Pocket ◽  
Ion Composition ◽  
Agrobacterium Radiobacter ◽  
Substrate Binding Pocket ◽  
Environmental Pressures ◽  
Degrading Enzyme ◽  
Protonation Equilibrium ◽  
Reaction Models ◽  
Bond Network

The OP (organophosphate)-degrading enzyme from Agrobacterium radiobacter (OpdA) is a binuclear metallohydrolase able to degrade highly toxic OP pesticides and nerve agents into less or non-toxic compounds. In the present study, the effect of metal ion substitutions and site-directed mutations on the catalytic properties of OpdA are investigated. The study shows the importance of both the metal ion composition and a hydrogen-bond network that connects the metal ion centre with the substrate-binding pocket using residues Arg254 and Tyr257 in the mechanism and substrate specificity of this enzyme. For the Co(II) derivative of OpdA two protonation equilibria (pKa1 ~5; pKa2 ~10) have been identified as relevant for catalysis, and a terminal hydroxide acts as the likely hydrolysis-initiating nucleophile. In contrast, the Zn(II) and Cd(II) derivatives only have one relevant protonation equilibrium (pKa ~4–5), and the μOH is the proposed nucleophile. The observed mechanistic flexibility may reconcile contrasting reaction models that have been published previously and may be beneficial for the rapid adaptation of OP-degrading enzymes to changing environmental pressures.

Computational investigation of 2D 3d/4d hexagonal transition metal borides for metal-ion batteries

2021 ◽  
pp. 138404
Author(s):  
Qiu He ◽  
Zhaohuai Li ◽  
Wenshan Xiao ◽  
Chengyi Zhang ◽  
Yan Zhao
Keyword(s):  
Transition Metal ◽  
Metal Ion ◽  
Computational Investigation ◽  
Metal Borides

Aspects of high-resolution imaging with a scanning ion microprobe

1986 ◽  
Vol 44 ◽  
pp. 750-751
Author(s):  
R. Levi-Setti ◽  
J. M. Chabala ◽  
Y. L. Wang
Keyword(s):  
Metal Ion ◽  
Secondary Ion Mass Spectrometry ◽  
Chromatic Aberration ◽  
Ion Source ◽  
Ion Microprobe ◽  
Emission Pattern ◽  
Intrinsic Resolution ◽  
Resolution Imaging ◽  
20 Nm ◽  
Secondary Ion

We have shown the feasibility of 20 nm lateral resolution in both topographic and elemental imaging using probes of this size from a liquid metal ion source (LMIS) scanning ion microprobe (SIM). This performance, which approaches the intrinsic resolution limits of secondary ion mass spectrometry (SIMS), was attained by limiting the size of the beam defining aperture (5μm) to subtend a semiangle at the source of 0.16 mr. The ensuing probe current, in our chromatic-aberration limited optical system, was 1.6 pA with Ga+ or In+ sources. Although unique applications of such low current probes have been demonstrated,) the stringent alignment requirements which they imposed made their routine use impractical. For instance, the occasional tendency of the LMIS to shift its emission pattern caused severe misalignment problems.

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