Search results for "Isatin"
showing 4 items of 34 documents
Structural Origin of Metal Specificity in Isatin Hydrolase from Labrenzia aggregata Investigated by Computer Simulations.
2017
We performed quantum-chemical calculations, ab initio molecular dynamics, hybrid quantum mechanics/molecular mechanics (QM/MM) and enhanced sampling metadynamics simulations to investigate the origin of metal specificity in isatin hydrolase from Labrenzia aggregata. The peculiar octahedral binding geometry of the Mn2+ ion in the Michaelis complex includes both the isatin substrate and the catalytic water within the first coordination shell of the cation. Our calculations show that the same arrangement of the ligands cannot be efficiently achieved in the presence of other small divalent metal cations such as Zn2+ or Cu2+ . On the contrary, bulkier alkaline-earth cations such as Mg2+ , which …
N-Heterocyclic Carbene Catalyzed Asymmetric Synthesis of Pentacyclic Spirooxindoles via [3+3] Annulations of Isatin-Derived Enals and Cyclic N-Sulfon…
2019
A convenient enantioselective route to new types of pentacyclic spirooxindoles via [3+3] annulation reactions of isatin-derived enals and cyclic N-sulfonyl ketimines, using N-heterocyclic carbene (NHC) catalysis has been developed. The new protocol leads to pentacyclic spirooxindoles bearing a quaternary spirostereocenter in good yields and good to high enantiomeric ratios. peerReviewed
Intestinal filtration as a consequence of increased mucosal hydraulic permeability
1980
Two mechanisms have been proposed to explain the secretory action of laxative compounds in the intestine: 1. increase of the intracellular amount of cyclic adenosine monophosphate due to stimulation of the adenylate cyclase system and 2. inhibition of intestinal transfer processes, in particular the Na,K-ATPase activated sodium absorption. In a set of in vivo and in vitro experiments in rat colon it could be demonstrated that dihydroxy bile acids (deoxycholate) and diphenolic laxatives (oxyphenisatin) enhance the hydraulic permeability of the mucosal tissue. The permeability changes take place--and there is good experimental evidence--at the zonulae occludentes which bind the epithelial cel…
La dollarisation des économies émergentes
2002
Current discussions about dollarization/euroization are built on substitution models and cost/benefits analysis. This working paper aims to go beyond these explanations based on a functionalist definition of money. An institutionalist definition of money advocates analyzing de facto dollarization more broadly as a legitimacy crisis of the unit of account that damages monetary sovereignty and of whom authorities try to check in a kind o f institutional resistance. A macroeconomic definition of money involves questionning full and de jure dollarization consistency with both of principles guiding the monetary economy of production: (1) endogeneity of money; (2) merger between monetary space an…