La(III)-hydrogen peroxide cooperativity in phosphate diester cleavage. A mechanistic study
- McGill Univ., Montreal (Canada)
La(III), Pr(III), Nd(III), and Eu(III) (2 mM) can each combine with hydrogen peroxide to provide close to 9 orders of magnitude rate acceleration for hydrolyzing BNPP (bis(p-nitrophenyl) phosphate) at pH 7 and 25{degree}C. The rate of the reaction is second order each in [(III)] and [H{sub 2}O{sub 2}], indicating that the active core 4 of the catalyst consists of two La(III) with two peroxides. The equilibrium constant for binding of BNPP to 4 (K{sub 1} = (1.3 {+-} 0.1) x 10{sup +3} M{sup -1}) and the rate constant for hydrolysis of the bound phosphate (k{sub 2} = (1.8 {+-} 0.1) x 10{sup -7} 5{sup -1}) have been determined. {sup 18}O labeling studies reveal that the peroxide is a nucleophilic catalyst in cleaving the diester. 17 refs., 5 figs., 1 tab.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 102737
- Journal Information:
- Journal of the American Chemical Society, Vol. 117, Issue 33; Other Information: PBD: 23 Aug 1995
- Country of Publication:
- United States
- Language:
- English
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