New Anion Exchangeable Layered Mixed Basic Salt, Ni1-xZn2x(OH)2(OCOCH3)2x·nH2O

1994 ◽  
Vol 371 ◽  
Author(s):  
Shoji Yamanaka ◽  
Kazunari Ando ◽  
Masao Ohashi
Keyword(s):  
Layered Compound ◽  
Zinc Ions ◽  
Two Dimensional ◽  
Basic Salt ◽  
Weakly Bound ◽  
Nickel Ions ◽  
Tetrahedral Sites ◽  
Inorganic As ◽  
Silicate Layers ◽  
Hydrolysis Of

AbstractA new anion exchangeable layered compound with a composition of Ni1-xZn2x(OH)2(OCOCH3)2x·nH2O (0.15 < x < 0.25) was prepared by hydrothermal hydrolysis of Ni-Zn mixed acetate solutions. The structure is related to zinc basic salts such as Zn5(OH)8Cl2·nH2O and Zn5(OH)8Cl2·nH2O; nickel ions form brucite-type hydroxide layers with vacanciesNi1-x(OH)2, and zinc ions occupy the tetrahedral sites above and below the vacant sites outside the hydroxide layers. Acetate ions are weakly bound to the Zn2+ ions, completing the tetrahedra, and easily exchanged with most of inorganic as well as organic anions. The reactions are reversible. Exchange with [Si8O20]8- ions resulted in the formation of two-dimensional silicate layers analogous to those of 2:1 type clay minerals.

Tubulin structure at intermediate resolution

1995 ◽  
Vol 53 ◽  
pp. 852-853
Author(s):  
K. H. Downing ◽  
S. G. Wolf ◽  
E. Nogales
Keyword(s):  
High Resolution ◽  
Structural Data ◽  
Therapeutic Drug ◽  
Zinc Ions ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Negative Stain ◽  
Functional Mechanisms ◽  
Tubulin Structure

Microtubules are involved in a host of critical cell activities, many of which involve transport of organelles through the cell. Different sets of microtubules appear to form during the cell cycle for different functions. Knowledge of the structure of tubulin will be necessary in order to understand the various functional mechanisms of microtubule assemble, disassembly, and interaction with other molecules, but tubulin has so far resisted crystallization for x-ray diffraction studies. Fortuitously, in the presence of zinc ions, tubulin also forms two-dimensional, crystalline sheets that are ideally suited for study by electron microscopy. We have refined procedures for forming the sheets and preparing them for EM, and have been able to obtain high-resolution structural data that sheds light on the formation and stabilization of microtubules, and even the interaction with a therapeutic drug.Tubulin sheets had been extensively studied in negative stain, demonstrating that the same protofilament structure was formed in the sheets and microtubules. For high resolution studies, we have found that the sheets embedded in either glucose or tannin diffract to around 3 Å.

Mechanics of free-standing inorganic and molecular 2D materials

Nanoscale ◽  
2021 ◽  
Author(s):  
Xianghui Zhang ◽  
Andre Beyer
Keyword(s):  
Recent Progress ◽  
Mechanical Characterization ◽  
2D Materials ◽  
Two Dimensional ◽  
Free Standing ◽  
Inorganic As

The discovery of graphene has triggered a great interest in inorganic as well as molecular two-dimensional (2D) materials. In this review, we summarize recent progress in the mechanical characterization of...

scholarly journals Chicken Intestinal Alkaline Phosphatase

1960 ◽  
Vol 43 (6) ◽  
pp. 1149-1169 ◽  
Author(s):  
M. Kunitz
Keyword(s):  
Alkaline Phosphatase ◽  
Zinc Ions ◽  
Magnesium Ions ◽  
Intestinal Alkaline Phosphatase ◽  
Reversible Inactivation ◽  
Higher Temperature ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Zn Ions ◽  
Denaturation Of Proteins

Purified chicken intestinal alkaline phosphatase is active at pH 8 to 9, but becomes rapidly inactivated with change of pH to 6 or less. Also, a solution of the inactivated enzyme at pH 4.5 rapidly regains its activity at pH 8. In the range of pH 6 to 8 a solution of purified alkaline phosphatase consists of a mixture of active and inactive enzyme in equilibrium with each other. The rate of inactivation at lower pH and of reactivation at higher pH increases with increase in temperature. Also, the activity at equilibrium in the range of pH 6 to 8 increases with temperature so that a solution equilibrated at higher temperature loses part of its activity on cooling, and vice versa, a rise in temperature shifts the equilibrium toward higher activity. The kinetics of inactivation of the enzyme at lower pH and the reactivation at higher pH is that of a unimolecular reaction. The thermodynamic values for the heat and entropy of the reversible inactivation and reactivation of the enzyme are considerably lower than those observed for the reversible denaturation of proteins. The inactivated enzyme at pH 4 to 6 is rapidly reactivated on addition of Zn ions even at pH 4 to 6. However, zinc ions are unable to replace magnesium ions as cocatalysts for the enzymatic hydrolysis of organic phosphates by alkaline phosphatase.

Two-dimensional Dirac dispersion in the layered compound BaCdSb2

2021 ◽  
Vol 103 (7) ◽  
Author(s):  
Dong-Yun Chen ◽  
Jin Cao ◽  
Botao Fu ◽  
Yongkai Li ◽  
Xiaoxiong Wang ◽  
...  
Keyword(s):  
Layered Compound ◽  
Two Dimensional

scholarly journals An ideal Josephson junction in an ultracold two-dimensional Fermi gas

Science ◽  
2020 ◽  
Vol 369 (6499) ◽  
pp. 89-91 ◽  
Author(s):  
Niclas Luick ◽  
Lennart Sobirey ◽  
Markus Bohlen ◽  
Vijay Pal Singh ◽  
Ludwig Mathey ◽  
...  
Keyword(s):  
Josephson Junction ◽  
High Temperature Superconductors ◽  
Fermi Gas ◽  
Current Phase ◽  
Strongly Correlated ◽  
Two Dimensional ◽  
Weakly Bound ◽  
Ideal Model System ◽  
Sinusoidal Current ◽  
2D Fermi Gas

The role of reduced dimensionality in high-temperature superconductors is still under debate. Recently, ultracold atoms have emerged as an ideal model system to study such strongly correlated two-dimensional (2D) systems. Here, we report on the realization of a Josephson junction in an ultracold 2D Fermi gas. We measure the frequency of Josephson oscillations as a function of the phase difference across the junction and find excellent agreement with the sinusoidal current phase relation of an ideal Josephson junction. Furthermore, we determine the critical current of our junction in the crossover from tightly bound molecules to weakly bound Cooper pairs. Our measurements clearly demonstrate phase coherence and provide strong evidence for superfluidity in a strongly interacting 2D Fermi gas.

4-Chloropyridine-3-sulfonic acid

2006 ◽  
Vol 62 (4) ◽  
pp. o1490-o1491
Author(s):  
Xin-Biao Mao ◽  
Tie-Han Li ◽  
Chun-An Ma ◽  
Qing-Bao Song
Keyword(s):  
Crystal Structure ◽  
Hydrochloric Acid ◽  
Hydrogen Bonds ◽  
Sulfonic Acid ◽  
Dilute Hydrochloric Acid ◽  
Two Dimensional ◽  
One Dimensional ◽  
Compound C ◽  
Dimensional Network ◽  
Hydrolysis Of

The title compound, C5H4ClNO3S, was obtained by hydrolysis of 4-chloropyridine-3-sulfonamide in dilute hydrochloric acid. In the crystal structure, one-dimensional chains are formed via N—H...O hydrogen bonds. In addition, weak C—H...Cl hydrogen bonds link these chains into a two-dimensional network

scholarly journals LAC4 IS THE STRUCTURAL GENE FOR β-GALACTOSIDASE IN KLUYVEROMYCES LACTIS

Genetics ◽  
1981 ◽  
Vol 98 (4) ◽  
pp. 729-745
Author(s):  
R Michael Sheetz ◽  
Robert C Dickson
Keyword(s):  
Thermal Stability ◽  
Structural Gene ◽  
Gel Electrophoresis ◽  
Kluyveromyces Lactis ◽  
Two Dimensional ◽  
Galactosidase Activity ◽  
Wild Type ◽  
Nonsense Suppressor ◽  
Hydrolysis Of ◽  
Thermal Stability Of

ABSTRACT Using genetic and biochemical techniques, we have determined that β-galactosidase in the yeast Kluyveromyces lactis is coded by the LAC4 locus. The following data support this conclusion: (1) mutations in this locus result in levels of β-galactosidase activity 100-fold lower than levels in uninduced wild type and all other lac- mutants; (2) three of five lac4 mutations are suppressible by an unlinked suppressor whose phenotype suggests that it codes for a nonsense suppressor tRNA; (3) a Lac+ revertant, bearing lac4–14 and this unlinked suppressor, has subnormal levels of β-galactosidase activity, and the Km for hydrolysis of o-nitrophenyl-β, D-galactoside and the thermal stability of the enzyme are altered; (4) the level of β-galactosidase activity per cell is directly proportional to the number of copies of LAC4; (5) analysis of cell-free extracts of strains bearing mutations in LAC4 by two-dimensional acryl-amide gel electrophoresis shows that strains bearing lac4–23 and lac4–30 contain an inactive β-galactosidase whose subunit co-electrophoreses with the wild-type subunit, while no subunit or fragment of the subunit is obs0ervable in lac4–8, lac4–14 or lac4–29 mutants; (6) of all lac4 mutants, only those bearing lac4–23 or lac4–30 contain a protein that cross-reacts with anti-β-galactosidase antibody, a finding consistent with the previous result; and (7) β-galactosidase activity in several Lac+ revertants of strains carrying lac4–23 or lac4–30 has greatly decreased thermostability.

scholarly journals Structure of 4-pyridoxolactonase fromMesorhizobium loti

2014 ◽  
Vol 70 (4) ◽  
pp. 424-432
Author(s):  
Jun Kobayashi ◽  
Yu Yoshikane ◽  
Toshiharu Yagi ◽  
Seiki Baba ◽  
Kimihiko Mizutani ◽  
...  
Keyword(s):  
Lactone Ring ◽  
Complex Structure ◽  
Docking Simulation ◽  
Competitive Inhibitor ◽  
Degradation Pathway ◽  
Vitamin B ◽  
Zinc Ions ◽  
Mesorhizobium Loti ◽  
Class B ◽  
Hydrolysis Of

4-Pyridoxolactonase fromMesorhizobium loticatalyzes the zinc-dependent lactone-ring hydrolysis of 4-pyridoxolactone (4PAL) to 4-pyridoxic acid (4PA) in vitamin B6degradation pathway I. The crystal structures of 4-pyridoxolactonase and its complex with 5-pyridoxolactone (5PAL; the competitive inhibitor) were determined. The overall structure was an αβ/βα sandwich fold, and two zinc ions were coordinated. This strongly suggested that the enzyme belongs to subclass B3 of the class B β-lactamases. In the complex structure, the carbonyl group of 5PAL pointed away from the active site, revealing why it acts as a competitive inhibitor. Based on docking simulation with 4PAL, 4PA and a reaction intermediate, 4-pyridoxolactonase probably catalyzes the reaction through a subclass B2-like mechanism, not the subclass B3 mechanism.

Sign in / Sign up

Export Citation Format

Share Document