Cleaving DNA-model phosphodiester with Lewis acid–base catalytic sites in bifunctional Zr–MOFs

2019 ◽  
Vol 48 (23) ◽  
pp. 8044-8048 ◽  
Author(s):  
Ying-Hua Zhou ◽  
Zhiyan Zhang ◽  
Margaret Patrick ◽  
Fan Yang ◽  
Rangling Wei ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Active Sites ◽  
Lewis Base ◽  
Zinc Hydroxide ◽  
Acid Base ◽  
Enhanced Activity ◽  
Nitrophenyl Phosphate ◽  
Catalytic Sites ◽  
Catalytic Active Sites ◽  
Hydrolysis Of

UiO-67-bpydc-Zn with isolated multi-catalytic active sites was fabricated as a catalyst for the hydrolysis of bis(p-nitrophenyl) phosphate as a DNA model. The enhanced activity may likely be attributed to the cooperation effects between the Lewis acid from the zirconium center at the node and the zinc hydroxide Lewis base in the linkers.

scholarly journals Interplay of hemilability and redox activity in models of hydrogenase active sites

2017 ◽  
Vol 114 (46) ◽  
pp. E9775-E9782 ◽  
Author(s):  
Shengda Ding ◽  
Pokhraj Ghosh ◽  
Marcetta Y. Darensbourg ◽  
Michael B. Hall
Keyword(s):  
Lewis Acid ◽  
Hydrogen Evolution Reaction ◽  
Resting State ◽  
Active Sites ◽  
Reductive Elimination ◽  
Lewis Base ◽  
Redox Activity ◽  
Production Mechanism ◽  
Acid Base ◽  
Redox Active

The hydrogen evolution reaction, as catalyzed by two electrocatalysts [M(N2S2)·Fe(NO)2]+, [Fe-Fe]+ (M = Fe(NO)) and [Ni-Fe]+ (M = Ni) was investigated by computational chemistry. As nominal models of hydrogenase active sites, these bimetallics feature two kinds of actor ligands: Hemilabile, MN2S2 ligands and redox-active, nitrosyl ligands, whose interplay guides the H2 production mechanism. The requisite base and metal open site are masked in the resting state but revealed within the catalytic cycle by cleavage of the MS–Fe(NO)2 bond from the hemilabile metallodithiolate ligand. Introducing two electrons and two protons to [Ni-Fe]+ produces H2 from coupling a hydride temporarily stored on Fe(NO)2 (Lewis acid) and a proton accommodated on the exposed sulfur of the MN2S2 thiolate (Lewis base). This Lewis acid–base pair is initiated and preserved by disrupting the dative donation through protonation on the thiolate or reduction on the thiolate-bound metal. Either manipulation modulates the electron density of the pair to prevent it from reestablishing the dative bond. The electron-buffering nitrosyl’s role is subtler as a bifunctional electron reservoir. With more nitrosyls as in [Fe-Fe]+, accumulated electronic space in the nitrosyls’ π*-orbitals makes reductions easier, but redirects the protonation and reduction to sites that postpone the actuation of the hemilability. Additionally, two electrons donated from two nitrosyl-buffered irons, along with two external electrons, reduce two protons into two hydrides, from which reductive elimination generates H2.

An uncoordinatedly tertiary nitrogen based tricarboxylate Calcium network with Lewis acid-base dual catalytic sites for cyanosilylation of aldehydes

2020 ◽  
Author(s):  
Xian-Ming Zhang ◽  
Ying-Xia Wang ◽  
Hui-Min Wang ◽  
Pan Meng ◽  
Dong-Xia Song ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Efficient Method ◽  
High Efficiency ◽  
Acid Base ◽  
Catalytic Sites ◽  
Tertiary Nitrogen

The design and utilization of dual sites for synergistic catalysts has been recognised as an efficient method towards high-efficiency catalysis in the cyanosilylation of aldehydes, which gives the key intermediates...

Solar-Driven Glucose Isomerization into Fructose via Transient Lewis Acid–Base Active Sites

ACS Catalysis ◽  
2021 ◽  
pp. 12170-12178
Author(s):  
Jiu Wang ◽  
Heng Zhao ◽  
Bicheng Zhu ◽  
Stephen Larter ◽  
Shaowen Cao ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Active Sites ◽  
Acid Base ◽  
Glucose Isomerization

The structure and activity of potassium supported on SBA-15 molecular sieve: Density functional theory study

2014 ◽  
Vol 13 (01) ◽  
pp. 1350076 ◽  
Author(s):  
Bing Liu ◽  
Daxi Wang ◽  
Zhongxue Wang ◽  
Zhen Zhao ◽  
Yu Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Lewis Acid ◽  
Molecular Sieve ◽  
Active Sites ◽  
Density Functional ◽  
Structural Model ◽  
Vibrational Frequencies ◽  
Oxygen Molecule ◽  
Lewis Base ◽  
Functional Theory

The geometries, vibrational frequencies, electronic properties and reactivity of potassium supported on SBA-15 have been theoretically investigated by the density functional theory (DFT) method. The structural model of the potassium supported on SBA-15 was constructed based on our previous work [Wang ZX, Wang DX, Zhao Z, Chen Y, Lan J, A DFT study of the structural units in SBA-15 mesoporous molecular sieve, Comput. Theor. Chem.963, 403, 2011]. This paper is the extension of our previous work. The most favored location of potassium atom was obtained by the calculation of substitution energy. The calculated vibrational frequencies of K /SBA-15 are in good agreement with the experimental results. By analyzing the properties of electronic structure, we found that the O atom of Si - O (2)- K group acts as the Lewis base center and the K atom acts as the Lewis acid center. The reactivity of K /SBA-15 was investigated by calculating the activation of oxygen molecule. The oxygen molecule can be activated by K /SBA-15 with an energy barrier of 103.2 kJ/mol. In the final state, the activated oxygen atoms become new Lewis acid centers, which are predicted to act as the active sites in the catalytic reactions. This study provides a deep insight into the properties of supported potassium catalysts and offers fundamental information for further research.

The protease MBTPS2 is an important regulator of several cellular processes, especially in health and sickness

2021 ◽  
Author(s):  
Moataz Dowaidar
Keyword(s):  
Active Sites ◽  
Peptide Bond ◽  
Cellular Processes ◽  
Disease States ◽  
Tremendous Progress ◽  
Catalytic Sites ◽  
Important Regulator ◽  
Catalytic Active Sites ◽  
Proteolytic Action ◽  
Health And Sickness

Since the identification of MBTPS2 in 1997, tremendous progress has been made in determining the protease's functions. The protease has developed from an element of the SREBP cleavage machinery to an important regulator of several cellular processes, especially in health and sickness. With this newfound information from biochemical and structural biology, S2P's proteolytic action through peptide bond hydrolysis can occur in the membrane, providing a conceptual framework for appreciating S2P's roles in other aspects, and showing that many other substrates rely on S2P for their survival. In addition, we discovered the identity of both of S2P's catalytic active sites, an essential finding as the activity of the proteolysis as well as the pathogenesis of MBTPS2-caused illnesses seems to be connected to the molecular and biochemical features of the catalytic sites. Additionally, MBTPS2 causes different diseases, possibly illustrating the pleiotropic nature of the protein. Also, while the ailments reported thus far are all due to mutations that cause MBTPS2 to lose function, other variants that cause MBTPS2 to be hyperactive have not been examined. Nevertheless, recognizing the related sickness pathomechanism is a challenge. Pursuing these challenging technical areas would most definitely enhance our understanding of MBTPS2 in disease states. MBTPS2 appears to be nearing the solution to many of the remaining fundamental questions surrounding the mechanism of its action, as well as being a therapeutic target for new therapies.

New insights into lactase and glycosylceramidase activities of rat lactase-phlorizin hydrolase

1989 ◽  
Vol 257 (4) ◽  
pp. G616-G623 ◽  
Author(s):  
H. A. Buller ◽  
A. G. Van Wassenaer ◽  
S. Raghavan ◽  
R. K. Montgomery ◽  
M. A. Sybicki ◽  
...  
Keyword(s):  
Active Sites ◽  
Specific Activity ◽  
Fold Increase ◽  
Developmental Pattern ◽  
Lactose Hydrolysis ◽  
Adult Males ◽  
Lactase Activity ◽  
Developmental Patterns ◽  
Catalytic Sites ◽  
Hydrolysis Of

Lactase-phlorizin hydrolase, a small intestinal disaccharidase, has been considered mainly an enzyme important only for the hydrolysis of lactose. After weaning in most mammals lactase-specific activity falls markedly, and, functionally, adult mammals are considered to be lactase deficient. However, the persistence of low levels of lactase activity in adulthood has never been explained. In addition, it has been suggested that lactase-phlorizin hydrolase is associated with glycosylceramidase activity when the enzyme is prepared by column chromatography, but it is unclear whether this represents copurified activities or two catalytic sites on one peptide. The developmental patterns of lactase-phlorizin hydrolase and other disaccharidases were investigated in homogenates of total rat small intestine; lactase and several glycosylceramidases were measured in immunoprecipitates from these homogenates using a monoclonal antibody. The developmental pattern of total lactase activity showed a steady 2.3-fold increase to adult levels (specific activity decreased eightfold), whereas total phlorizin-hydrolase activity increased 10.7-fold (specific activity decreased threefold). As expected, levels of both total and specific sucrase and maltase activities increased during development. In lactating rats total lactase activity showed a significant increase compared with adult males. The developmental pattern of the enzyme activities for the glycolipid substrates was similar to that found for lactase, and the immunoprecipitated enzyme showed a 40- to 55-fold higher affinity for the glycolipids than for lactose. Galactosyl- and lactosylceramide inhibited lactose hydrolysis by 38%, without a competitive pattern, suggesting two different active sites for lactose and glycolipid hydrolysis, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Synthetic Peptides as Structural Maquettes of Angiotensin-I Converting Enzyme Catalytic Sites

2010 ◽  
Vol 2010 ◽  
pp. 1-13 ◽  
Author(s):  
Zinovia Spyranti ◽  
Athanassios S. Galanis ◽  
George Pairas ◽  
Georgios A. Spyroulias ◽  
Evy Manessi-Zoupa ◽  
...  
Keyword(s):  
Synthetic Peptides ◽  
Active Sites ◽  
Rational Design ◽  
Transmembrane Domain ◽  
Structural Investigations ◽  
Catalytic Sites ◽  
High Resolution Structure ◽  
Catalytic Active Sites ◽  
Hydrophobic Transmembrane Domain ◽  
Highly Hydrophobic

The rational design of synthetic peptides is proposed as an efficient strategy for the structural investigation of crucial protein domains difficult to be produced. Only after half a century since the function of ACE was first reported, was its crystal structure solved. The main obstacle to be overcome for the determination of the high resolution structure was the crystallization of the highly hydrophobic transmembrane domain. Following our previous work, synthetic peptides and Zinc(II) metal ions are used to build structural maquettes of the two Zn-catalytic active sites of the ACE somatic isoform. Structural investigations of the synthetic peptides, representing the two different somatic isoform active sites, through circular dichroism and NMR experiments are reported.

scholarly journals Structure investigations of group 13 organometallic carboxylates

2017 ◽  
Vol 46 (3) ◽  
pp. 669-677 ◽  
Author(s):  
Iwona Justyniak ◽  
Daniel Prochowicz ◽  
Adam Tulewicz ◽  
Wojciech Bury ◽  
Piotr Goś ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Lewis Acid ◽  
Relative Magnitude ◽  
Lewis Base ◽  
Acid Base ◽  
Group 13 ◽  
Structure Investigations

The effect of both the relative magnitude of electrophilicity of metal centres and the character of a Lewis base on the molecular structure of the electron-precise [R2M(μ-O2CPh)]2-type carboxylates and their Lewis acid–base adducts [(R2M)(μ-O2CPh)(py-Me)] is reported.

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