New Method for the Synthesis of a Mononucleating Cyclic Peptide Ligand, Crystal Structures of its Ni, Zn, Cu, and Co Complexes, and Their Inhibitory Bioactivity Against Urease

2007 ◽  
Vol 60 (5) ◽  
pp. 375 ◽  
Author(s):  
Kui Cheng ◽  
Zhong-Lu You ◽  
Hai-Liang Zhu
Keyword(s):  
Cyclic Peptide ◽  
Peptide Ligand ◽  
Jack Bean Urease ◽  
One Pot ◽  
Nickel Ion ◽  
Jack Bean ◽  
Metal Free ◽  
Synthetic Procedure ◽  
First Time ◽  
Solvothermal Conditions

A novel cyclic peptide complex, NiL 1 (H2L = 12,24-dihydroxy-1,6-dioxo-2,5,14,17-tetraaza[6*6]metacyclophane-13,17-diene has been synthesized for the first time under solvothermal conditions through a one-pot synthetic procedure using nickel ion as the template reagent. It was found that other metal ions were not suitable for the direct template reagent in this reaction. The nickel ion was eliminated from the complex and the metal-free cyclic peptide ligand H2L was obtained through a series of reactions. Then, ZnII, CuII, and CoII were coordinated with H2L under the same solvothermal conditions to produce three isomorphous complexes ZnL 2, CuL 3, and CoL 4. Their inhibitory bioactivities against urease were then studied. The copper(ii) complex 3 was the strongest inhibitor against jack bean urease, while H2L, 2, and 4 showed weak or no inhibitory activity against this enzyme.

Jack bean urease (EC 3.5.1.5). V. On the mechanism of action of urease on urea, formamide, acetamide, N-methylurea, and related compounds

1980 ◽  
Vol 58 (12) ◽  
pp. 1335-1344 ◽  
Author(s):  
Nicholas E. Dixon ◽  
Peter W. Riddles ◽  
Carlo Gazzola ◽  
Robert L. Blakeley ◽  
Burt Zerner
Keyword(s):  
Enzymatic Hydrolysis ◽  
Mechanism Of Action ◽  
Active Site ◽  
Ph Dependence ◽  
Jack Bean Urease ◽  
Nickel Ion ◽  
Jack Bean ◽  
First Time ◽  
Hydrolysis Of ◽  
Hydrolysis Of Urea

Acetamide and N-methylurea have been shown for the first time to be substrates for jack bean urease. In the enzymatic hydrolysis of urea, formamide, acetamide, and N-methylurea at pH 7.0 and 38 °C, kcat has the values 5870, 85, 0.55, and 0.075 s−1, respectively. The urease-catalyzed hydrolysis of all these substrates involves the active-site nickel ion(s). Enzymatic hydrolysis of the following compounds could not be detected: phenyl formate, p-nitroformanilide, trifluoroacetamide, p-nitrophenyl carbamate, thiourea, and O-methylisouronium ion. In the enzymatic hydrolysis of urea, the pH dependence of kcat between pH 3.4 and 7.8 indicates that at least two prototropic forms are active. Enzymatic hydrolysis of urea in the presence of methanol gave no detectable methyl carbamate. A mechanism of action for urease is proposed which involves initially an O-bonded complex between urea and an active-site Ni2+ ion and subsequently an O-bonded carbamato–enzyme intermediate.

Direct insight into crystallization and stability of hybrid perovskite CH3NH3PbI3via solvothermal synthesis

2015 ◽  
Vol 3 (31) ◽  
pp. 15854-15857 ◽  
Author(s):  
Ying Chen ◽  
Shuang Yang ◽  
Xiao Chen ◽  
Yi Chu Zheng ◽  
Yu Hou ◽  
...  
Keyword(s):  
Single Crystals ◽  
Solvothermal Synthesis ◽  
One Pot ◽  
Hybrid Perovskite ◽  
First Time ◽  
Solvothermal Conditions ◽  
Insight Into

We report a one-pot solvothermal approach to synthesize cuboid shaped CH3NH3PbI3 single crystals. Growth and dissolution phenomena of perovskite crystals were discovered for the first time under solvothermal conditions.

scholarly journals The nickel ion environment in jack bean urease

1984 ◽  
Vol 220 (2) ◽  
pp. 591-595 ◽  
Author(s):  
L Alagna ◽  
S S Hasnain ◽  
B Piggott ◽  
D J Williams
Keyword(s):  
Fine Structure ◽  
Structure Study ◽  
Jack Bean Urease ◽  
Model Compounds ◽  
Deprotonated Form ◽  
Nickel Ion ◽  
Edge Structure ◽  
Jack Bean ◽  
X Ray ◽  
X Ray Absorption

Preliminary results of an extended X-ray absorption fine structure (e.x.a.f.s.) and X-ray absorption near edge structure study of jack bean urease have recently been reported [Hasnain & Piggott (1983) Biochem. Biophys. Res. Commun. 112, 279]. These results indicate that the environment of the nickel ion in the enzyme is similar to that in the model compounds Ni(L)2(L')1(ClO4)1 (where L is 1-n-propyl-2-alpha-hydroxybenzylbenzimidazole and L' is the deprotonated form) and Ni(HMB)3(Br)2 (where HMB is 2-hydroxymethylbenzimidazole), the closest similarity being with Ni(L)2-(L')1(ClO4)1. A detailed e.x.a.f.s. analysis has now been carried out and the crystal structures of the two model compounds solved. These results are reported here.

Jack bean urease (EC 3.5.1.5). III. The involvement of active-site nickel ion in inhibition by β-mercaptoethanol, phosphoramidate, and fluoride

1980 ◽  
Vol 58 (6) ◽  
pp. 481-488 ◽  
Author(s):  
Nicholas E. Dixon ◽  
Robert L. Blakeley ◽  
Burt Zerner
Keyword(s):  
Dissociation Constant ◽  
Active Site ◽  
Competitive Inhibitor ◽  
Jack Bean Urease ◽  
Nickel Ion ◽  
Nickel Ions ◽  
Jack Bean ◽  
Complex Fluoride ◽  
Spectral Changes ◽  
Hydrolysis Of

Interaction of β-mercaptoethanol with urease produces large, rapid and fully reversible spectral changes in that part of the electronic absorption spectrum which is associated with the tightly bound nickel ions. The spectrophotometrically determined value of the dissociation constant of the β-mercaptoethanol–urease complex (0.95 ± 0.05 mM at pH 7.12 and 25 °C) is in agreement with the Ki (0.72 ± 0.26 mM) for β-mercaptoethanol acting as a competitive inhibitor in the hydrolysis of urea. This constitutes direct evidence that the nickel in jack bean urease is at the active site. Inhibition of urease by phosphoramidate is slowly achieved and slowly reversed, and upon reactivation of the isolated phosphoramidate–urease complex, phosphoramidate is regenerated in good yield. Spectrophotometric experiments indicate that phosphoramidate binds to nickel ion in urease. Competition with β-mercaptoethanol was used to determine a dissociation constant (1.23 ± 0.10 mM at pH 7.12 and 25 °C) for a fluoride–urease complex in which fluoride ion also coordinates with an active-site nickel ion. Kinetic evidence is presented which indicates that in the presence of urea, a ternary complex (fluoride–urea–urease) is formed.

Metal-Free Photoinduced Hydroalkylation Cascade Enabled by an Electron-Donor-Acceptor Complex

2020 ◽  
Author(s):  
José Tiago Menezes Correia ◽  
Gustavo Piva da Silva ◽  
Camila Menezes Kisukuri ◽  
Elias André ◽  
Bruno Pires ◽  
...  
Keyword(s):  
Electron Donor ◽  
Functional Group ◽  
Photoexcited Electron ◽  
One Pot ◽  
Quaternary Centers ◽  
Metal Free ◽  
Acceptor Complex ◽  
Catalyst Free ◽  
Donor Acceptor ◽  
Radical Cascade

A metal- and catalyst-free photoinduced radical cascade hydroalkylation of 1,7-enynes has been disclosed. The process is triggered by a SET event involving a photoexcited electron-donor-aceptor complex between NHPI ester and Hantzsch ester, which decomposes to afford a tertiary radical that is readily trapped by the enyne. <a>The method provides an operationally simple, robust and step-economical approach to the construction of diversely functionalized dihydroquinolinones bearing quaternary-centers. A sequential one-pot hydroalkylation-isomerization approach is also allowed giving access to a family of quinolinones. A wide substrate scope and high functional group tolerance was observed in both approaches</a>.

Metal-Free Photoredox-Catalyzed C–H/C–H Coupling of Arenes Enabled by Interrupted Pummerer Activation

2019 ◽  
Author(s):  
Miles Aukland ◽  
Mindaugas Šiaučiulis ◽  
Adam West ◽  
Gregory Perry ◽  
David Procter
Keyword(s):  
Natural Product ◽  
Selective Reduction ◽  
Cross Coupling ◽  
One Pot ◽  
Complex Molecules ◽  
Pummerer Reaction ◽  
Metal Free ◽  
Bond Forming ◽  
Coupling Partner ◽  
Bioactive Natural Product

<p>Aryl–aryl cross-coupling constitutes one of the most widely used procedures for the synthesis of high-value materials, ranging from pharmaceuticals to organic electronics and conducting polymers. The assembly of (hetero)biaryl scaffolds generally requires multiple steps; coupling partners must be functionalized before the key bond-forming event is considered. Thus, the development of selective C–H arylation processes in arenes, that side-step the need for prefunctionalized partners, is crucial for streamlining the construction of these key architectures. Here we report an expedient, one-pot assembly of (hetero)biaryl motifs using photocatalysis and two non-prefunctionalized arene partners. The approach is underpinned by the activation of a C–H bond in an arene coupling partner using the interrupted Pummerer reaction. A unique pairing of the organic photoredox catalyst and the intermediate dibenzothiophenium salts enables highly selective reduction in the presence of sensitive functionalities. The utility of the metal-free, one-pot strategy is exemplified by the synthesis of a bioactive natural product and the modification of complex molecules of societal importance.</p>

An Expeditious One-Pot Three-Component Synthesis of 4-Aryl-3,4-dihydrobenzo[g] quinoline-2,5,10(1H)-triones under Green Conditions

2020 ◽  
Vol 23 (23) ◽  
pp. 2626-2634
Author(s):  
Saiedeh Kamalifar ◽  
Hamzeh Kiyani
Keyword(s):  
Reaction Medium ◽  
Meldrum's Acid ◽  
Meldrum’S Acid ◽  
One Pot ◽  
One Pot Synthesis ◽  
Substituted Benzaldehydes ◽  
High Yields ◽  
First Time ◽  
Green Conditions

: An efficient and facial one-pot synthesis of 4-aryl-3,4-dihydrobenzo[g]quinoline- 2,5,10(1H)-triones was developed for the first time. The process proceeded via the three-component cyclocondensation of 2-amino-1,4-naphthoquinone with Meldrum’s acid and substituted benzaldehydes under green conditions. The fused 3,4-dihydropyridin-2(1H)- one-ring naphthoquinones have been synthesized with good to high yields in refluxing ethanol as a green reaction medium. This protocol is simple and effective as well as does not involve the assistance of the catalyst, additive, or hazardous solvents.

Metal-Free Synthesis of 1,2,4-Triazines via a Coupled Domino Process in One-Pot

2016 ◽  
Vol 21 (2) ◽  
pp. 183-188
Author(s):  
Jing Wang ◽  
Dong Tang ◽  
Zhuo-Mei Li ◽  
Ping Wu ◽  
Xu Meng ◽  
...  
Keyword(s):  
One Pot ◽  
Metal Free

Synthesis of Pyrrolo[1,2-a][1,6]- and [1,8]naphthyridines by Alkyne-Carbonyl Metathesis

Synthesis ◽  
2020 ◽  
Author(s):  
Peter Ehlers ◽  
Peter Langer ◽  
Marian Blanco Ponce ◽  
Silvio Parpart ◽  
Alexander Villinger ◽  
...  
Keyword(s):  
Heterocyclic Compounds ◽  
Metathesis Reaction ◽  
Synthetic Methodology ◽  
Facile Synthesis ◽  
Reaction Conditions ◽  
One Pot ◽  
Metal Free ◽  
Modular Synthesis

AbstractA concise and modular synthesis of pyrrolo[1,2-a][1,6]- and [1,8]naphthyridines by a one-pot two-step reaction consisting of electrophilic acylation followed by an alkyne-carbonyl-metathesis reaction as the final cyclization step is reported. This developed synthetic methodology allows the facile synthesis of these heterocyclic core structures in mainly high overall yields under metal-free conditions. Reaction conditions are carefully optimized and display a novel supplement to access these tricyclic heterocyclic compounds.

Catalyst-free synthesis of phenanthridines via electrochemical coupling of 2-isocyanobiphenyls and amines

2021 ◽  
Vol 45 (14) ◽  
pp. 6367-6378
Author(s):  
Bhanwar Kumar Malviya ◽  
Karandeep Singh ◽  
Pradeep K. Jaiswal ◽  
Manvika Karnatak ◽  
Ved Prakash Verma ◽  
...  
Keyword(s):  
One Pot ◽  
Metal Free ◽  
Catalyst Free ◽  
Electrochemical Coupling

One pot metal-free synthesis of phenanthridines and amides under electrochemical conditions.

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