Thesis (M.Sc.) -- University of Toronto, 1996.
|Series||Canadian theses = -- Thèses canadiennes|
|The Physical Object|
|Pagination||2 microfiches : negative. --|
The divalent metal ion-catalyzed hydrolysis of thionate (PS) and oxonate (PO) organophosphorus pesticides has been examined in light of three possible catalysis mech anisms: (1) metal ion. PAPs catalyze the hydrolysis of phosphate monoesters with mildly acidic pH optima (5–7) utilizing a binuclear metal center containing a ferric ion and a divalent metal ion. PAPs are also characterized by their purple color, the result of a tyrosine to Fe 3 + charge transfer transition at about nm. The mammalian enzymes are. Sodium N-I-Boc aminoacyl ethyl phosphates also react with lower alcohols and diols in water to form the corresponding amino acid esters. Divalent metal ions increase the reactivity of aminoacyl ethyl phosphates toward alcohols in aqueous solution. This may provide a route to the chemical aminoacylation of t-RNAAuthor: Peter C. Spencer. The slower rate of interaction between substrate and the Fe(3+) site relative to catalysis suggests that the substrate is hydrolyzed while coordinated only to the divalent metal ion.
Similarly, enzymes that catalyze the hydrolysis of phosphate ester bonds use the functional groups of amino acids in a concerted fashion with the Lewis acidity of metal ions. One well-studied example is staphylococcal nuclease, which uses the electrostatic properties of a protein-bound Ca(II) ion and general base catalysis to hydrolyze DNA. Other enzymes, such as carboxypeptidase, require metal ions as co-factors, the divalent cations Mg 2+, Zn 2+ and Mn 2+ being the most common; these are often called enzyme activators. Table lists several enzymes and their respective co-factors. (a) Two metal ions, a Mg 2+ and a Zn 2+, in the active site of PDE4 (ref. ) coordinate either a hydroxide ion or a water molecule (or conceivably an oxide ) and, along with an aspartate, are. Hydrolysis (/ h aɪ ˈ d r ɒ l ɪ s ɪ s /; from Ancient Greek hydro-, meaning 'water', and lysis, meaning 'to unbind') is any chemical reaction in which a molecule of water ruptures one or more chemical term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.. Biological hydrolysis is the cleavage of biomolecules where a water.
Utyanskaya EZ, Pavlovsky AG, Sosfenov NI, Shilov AE() Intermolecular association and general basic cataly sis in hydrolysis of adenosine-5′-triphosphoric acid, catalyzed by divalent metal ion. Kinetic Catalysis (Russ) – Google Scholar. The substrate-assisted general base catalysis model for phosphate monoester hydrolysis: evaluation using reactivity comparisons. Journal of the American Chemical Society , – Agirrezabala, X. & Frank, J. (). However, some of the species of Table 1 having a high potential, could be formed abiotically or at least without requiring catalysis, some of them, including acetyl phosphate (as other acyl and aminoacyl phosphates) and carbamyl phosphate, indeed still play a role in biochemistry. They could be considered as possible alternative energy shuttles. Acyl phosphates are among the more potent activated biochemicals. Values of their free energy of hydrolysis at pH 7 (ΔG°’) reach −43 kJ mol −1 for acetyl phosphate. By contrast with ATP and pyrophosphate, acyl phosphates and acyl adenylates bear a single negative charge at mildly acidic pH values and benefit to a much lesser degree.