Main-Chain Organometallic Microporous Polymers Bearing Triphenylene-Tris(N-Heterocyclic Carbene)-Gold Species: Catalytic Properties

2014 ◽  
Vol 20 (19) ◽  
pp. 5746-5751 ◽  
Author(s):  
Sergio Gonell ◽  
Macarena Poyatos ◽  
Eduardo Peris
Keyword(s):  
Main Chain ◽  
Catalytic Properties ◽  
Microporous Polymers

Main-Chain Organometallic Microporous Polymers Based on Triptycene: Synthesis and Catalytic Application in the Suzuki-Miyaura Coupling Reaction

2013 ◽  
Vol 19 (16) ◽  
pp. 5004-5008 ◽  
Author(s):  
Chun Zhang ◽  
Jing-Jing Wang ◽  
Ying Liu ◽  
Hui Ma ◽  
Xiang-Liang Yang ◽  
...  
Keyword(s):  
Main Chain ◽  
Coupling Reaction ◽  
Microporous Polymers ◽  
Catalytic Application

scholarly journals Non-Specific GH30_7 Endo-β-1,4-xylanase from Talaromyces leycettanus

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4614
Author(s):  
Katarína Šuchová ◽  
Nikolaj Spodsberg ◽  
Kristian B. R. Mørkeberg Krogh ◽  
Peter Biely ◽  
Vladimír Puchart
Keyword(s):  
General Formula ◽  
Main Chain ◽  
Catalytic Properties ◽  
Specific Activity ◽  
Side Chain ◽  
Biotechnological Applications ◽  
Xylose Residue ◽  
Great Tolerance ◽  
Chain Cleavage ◽  
Hydrolysis Of

This study describes the catalytic properties of a GH30_7 xylanase produced by the fungus Talaromyces leycettanus. The enzyme is an ando-β-1,4-xylanase, showing similar specific activity towards glucuronoxylan, arabinoxylan, and rhodymenan (linear β-1,3-β-1,4-xylan). The heteroxylans are hydrolyzed to a mixture of linear as well as branched β-1,4-xylooligosaccharides that are shorter than the products generated by GH10 and GH11 xylanases. In the rhodymenan hydrolyzate, the linear β-1,4-xylooligosaccharides are accompanied with a series of mixed linkage homologues. Initial hydrolysis of glucuronoxylan resembles the action of other GH30_7 and GH30_8 glucuronoxylanases, resulting in a series of aldouronic acids of a general formula MeGlcA2Xyln. Due to the significant non-specific endoxylanase activity of the enzyme, these acidic products are further attacked in the unbranched regions, finally yielding MeGlcA2Xyl2-3. The accommodation of a substituted xylosyl residue in the −2 subsite also applies in arabinoxylan depolymerization. Moreover, the xylose residue may be arabinosylated at both positions 2 and 3, without negatively affecting the main chain cleavage. The catalytic properties of the enzyme, particularly the great tolerance of the side-chain substituents, make the enzyme attractive for biotechnological applications. The enzyme is also another example of extraordinarily great catalytic diversity among eukaryotic GH30_7 xylanases.

Microstructure and reactivity of small metal particles: The role of Ce additives

1992 ◽  
Vol 50 (1) ◽  
pp. 318-319
Author(s):  
L.D. Schmidt ◽  
K. R. Krause ◽  
J. M. Schwartz ◽  
X. Chu
Keyword(s):  
Atmospheric Pressure ◽  
Noble Metals ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Chemical Shifts ◽  
Catalytic Converter ◽  
Structural Evolution ◽  
Single Particles ◽  
Small Metal Particles

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.

Electron distribution change of small nickel particles encaged in X zeolite in presence of Ce3+ ions, related to their catalytic properties

1986 ◽  
Vol 83 ◽  
pp. 619-621 ◽  
Author(s):  
F. Vergand ◽  
B. Iraqi ◽  
C. Bonnelle ◽  
E. Ramaroson ◽  
M.F. Guilleux ◽  
...  
Keyword(s):  
Electron Distribution ◽  
Catalytic Properties ◽  
Distribution Change ◽  
Nickel Particles ◽  
X Zeolite

On the Preparation of Bovine α-Thrombin

1978 ◽  
Vol 39 (01) ◽  
pp. 193-200 ◽  
Author(s):  
Erwin F Workman ◽  
Roger L Lundblad
Keyword(s):  
Immobilized Enzyme ◽  
Catalytic Properties ◽  
Specific Activity ◽  
Guanidine Hydrochloride ◽  
Low Molecular Weight ◽  
Reversible Process ◽  
Gel Beads ◽  
Tissue Thromboplastin ◽  
C 50 ◽  
Hydrolysis Of

SummaryAn improved method for the preparation of bovine α-thrombin is described. The procedure involves the activation of partially purified prothrombin with tissue thromboplastin followed by chromatography on Sulfopropyl-Sephadex C-50. The purified enzyme is homogeneous on polyacrylamide discontinuous gel electrophoresis and has a specific activity toward fibrinogen of 2,200–2,700 N.I.H. U/mg. Its stability on storage in liquid media is dependent on both ionic strenght and temperature. Increasing ionic strength and decreasing temperature result in optimal stability. The denaturation of α-thrombin by guanidine hydrochloride was found to be a partially reversible process with the renatured species possessing properties similar to “aged” thrombin. In addition, the catalytic properties of a-thrombin covalently attached to agarose gel beads were also examined. The activity of the immobilized enzyme toward fibrinogen was affected to a much greater extent than was the hydrolysis of low molecular weight, synthetic substrates.

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