Inclusion Compounds. XVIII.¹ The Catalysis of the Fission of Pyrophosphates by Cyclodextrin. A Model Reaction for the Mechanism of Enzymes

A catalyst for ester hydrolysis showing electrostatic and hydrophobic binding properties

“…Furthermore, most of these studies used linear alkyl chains as binding groups (2-6): it has recently been shown that compounds with long alkyl chains are aggregated at much lower concentrations than had been believed (8,9), so that there is some doubt about the interpretation of the large rate enhancements reported for these compounds (10). Enzyme models based upon cyclodextrins circumvent some of these difficulties, in that both binding constants and rate constants for reaction within the complex are measureable (11)(12)(13)(14)(15)(16)(17)(18). Unfortunately, only limited variation of either the binding group of the substrate or of the cyclodextrin is possible, and it is difficult to generalize from the behavior of these systems because of the rather heterogeneous chemical nature of the inner surface of the cyclodextrin binding cavity.…”

Stabilization of the pesticide Fenitrothion towardOandNnucleophiles in the presence of cyclodextrins

“…Reaction pathway d) in Scheme 4 that implies that the aminolysis reaction occurs when the substrate and the amine are complexed each of them with one CD can be discarded on the following bases: (i) crystallographic data, [30] molecular docking calculations [31] and kinetic studies, [7] indicate that Fenitrothion includes in the cavity of one CD, preferably through the thiophosphate group (reaction center); (ii) a second-order dependence on CD concentration, [CD] 2 , is not observed from the plots of k The observed rate constant for the mechanism in Scheme 5 is given by Eqn (17) that has the same mathematical form of Eqn (1) with a and b given by Eqns (18) and (19). In that equation, k A is the sum of k …”

“…[18] There are several examples in the literature of changes in reaction rates due to the presence of linear sugars or monosaccharides. [19][20][21][22] The inhibition produced by complexation with β-CD is greater for the reaction of 1 with HOO À than for the hydrolysis reaction. If the reaction center is buried in the CD's cavity, the reaction with a bulkier nucleophile would lead to a greater inhibition as it is observed when we compared the reactions with HOO À or HO À .…”

Acceleration of Thiol Ester Hydrolysis by Cyclodextrins: Evidence from Rate and Computational Studies

“…[6] The hydrolysis of diaryl pyrophosphate in the presence of calcium ions is catalyzed by cyclodextrins and in this reaction a transfer of the phosphate residue to the cyclodextrin is observed. [7] Tee et al have extensively studied [8][9][10][11] the hydrolysis of substituted phenyl acetates by CDs in basic aqueous solution and also the basic hydrolysis of 1-naphthyl acetate and 2-naphthyl acetate in presence of cyclodextrin, which show that these two positional isomers differ significantly towards the cyclodextrin-catalyzed hydrolysis. [8,9] Chain length effects in the cleavage of aryl esters by cyclodextrins is studied and different transition states from m-and p-nitrophenyl alkanoates with cyclodextrin [10] are proposed.…”