Metal Complexes with Macrocyclic Ligands. Part XXVII. Cu2+-promoted hydrolysis of carboxylic- and phosphonic-acid esters in the side chain of tetraazamacrocycles

1989 ◽  
Vol 72 (1) ◽  
pp. 131-138 ◽  
Author(s):  
Daniel Tschudin ◽  
Andreas Riesen ◽  
Thomas A. Kaden
Keyword(s):  
Metal Complexes ◽  
Phosphonic Acid ◽  
Macrocyclic Ligands ◽  
Side Chain ◽  
Hydrolysis Of ◽  
Acid Esters

scholarly journals Substrate Inhibition in the Hydrolysis of Hippuric Acid Esters by Carboxypeptidase A

1975 ◽  
Vol 53 (2) ◽  
pp. 283-294 ◽  
Author(s):  
Joe Murphy ◽  
John W. Bunting
Keyword(s):  
Substrate Concentration ◽  
Hippuric Acid ◽  
Substrate Inhibition ◽  
Competitive Inhibitor ◽  
Side Chain ◽  
Carboxypeptidase A ◽  
Substrate Activation ◽  
Hydrolysis Of ◽  
Substrate Concentrations ◽  
Acid Esters

The dependence of initial velocity upon substrate concentration has been examined in the carboxypeptidase A catalyzed hydrolysis of the following hippuric acid esters (at pH 7.5, 25°, ionic strength O.5): C6H5CONHCH2CO2CHRCO2H: R=CH3; CH2CH3;(CH2)2CH3; (CH2)3CH3; (CH2)5CH3; CH(CH3)2; CH2CH(CH3)2; C6H5; CH2C6H5. All of these esters display marked substrate inhibition of their enzymic hydrolyses. With the exception of R=CH3, the velocity-substrate concentration profiles for each of these esters can be rationalized by the formation of an E.S2 complex which, independent of the alcohol moiety of the ester, reacts approximately 25 times more slowly than the E.S complex. For most of these esters, the formation of E.S2 approximates ordered binding of the substrate molecules at the catalytic and inhibitory sites. While binding at the catalytic site is markedly dependent on the nature of the R group, binding of a second substrate molecule to E.S is not significantly affected by the nature of the R side chain. For R=C6H5, the D ester is neither a substrate nor a competitive inhibitor of the hydrolysis of the L-ester but can replace the L-ester at the binding site which is responsible for substrate inhibition. The kinetic analysis suggests that this behavior of D and L -enantiomers is also typical of the other esters examined (except possibly R=CH3). For R=CH3 only, substrate activation also seems to occur prior to the onset of substrate inhibition at higher substrate concentrations.

Supramolecular catalytic system triton X-100-polyethyleneimine-La(III) for hydrolysis of phosphonic acid esters

2011 ◽  
Vol 52 (1) ◽  
pp. 55-61 ◽  
Author(s):  
Yu. R. Kudryashova ◽  
F. G. Valeeva ◽  
A. R. Ibragimova ◽  
L. Ya. Zakharova ◽  
A. I. Konovalov
Keyword(s):  
Catalytic System ◽  
Phosphonic Acid ◽  
Triton X ◽  
Hydrolysis Of ◽  
Acid Esters

Dicationic surfactant based catalytic systems for alkaline hydrolysis of phosphonic acid esters

2012 ◽  
Vol 53 (2) ◽  
pp. 206-213 ◽  
Author(s):  
A. B. Mirgorodskaya ◽  
F. G. Valeeva ◽  
S. S. Lukashenko ◽  
E. I. Yatskevich ◽  
L. Ya. Zakharova ◽  
...  
Keyword(s):  
Phosphonic Acid ◽  
Alkaline Hydrolysis ◽  
Catalytic Systems ◽  
Hydrolysis Of ◽  
Acid Esters

The Effect of N-Substitution on the Rates of Saponification of Some Amino Acid Esters

1971 ◽  
Vol 49 (21) ◽  
pp. 3468-3476 ◽  
Author(s):  
Jocelyn E. Purdie ◽  
N. Leo Benoiton
Keyword(s):  
Amino Acid ◽  
Methyl Esters ◽  
Activation Parameters ◽  
Side Chain ◽  
Amino Acid Esters ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Hydrolysis Of ◽  
Acid Esters

The saponification rates (measured at 25 ° by a titrimetric method) of the unprotonated forms of the methyl esters of glycine, alanine, leucine, valine, and phenylalanine were compared with those of the N-methyl, the N-acetyl, and the N-acetyl, N-methylamino acid analogues. N-Acetylation slightly increased or decreased the rate but N-methylation caused a reduction by as much as a factor of ten, depending on the complexity of the side-chain. The esters of the N-acetyl, N-methylamino acids, which exist as cis and trans isomers, were saponified at rates intermediate between those of the esters of the N-acetylamino acids and N-methylamino acids. Activation parameters were obtained for the phenylalanine and leucine derivatives. N-Methylation resulted in an increase in ΔH≠ and ΔS≠ which was attributed in part to solvation effects. The hydrolysis of the cationic esters of glycine and alanine was still evident at pH 11.0. N-Methylation had little effect on the rates of saponification of the charged forms.

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