Questioning the paradigm of metal complex promoted phosphodiester hydrolysis: [Mo7O24]6−polyoxometalate cluster as an unlikely catalyst for the hydrolysis of a DNA model substrate

2008 ◽  
pp. 85-87 ◽  
Author(s):  
Els Cartuyvels ◽  
Gregory Absillis ◽  
Tatjana N. Parac-Vogt
Keyword(s):  
Metal Complex ◽  
Phosphodiester Hydrolysis ◽  
Hydrolysis Of

scholarly journals Pseudomonas putida MPE, a manganese-dependent endonuclease of the binuclear metallophosphoesterase superfamily, incises single-strand DNA in two orientations to yield a mixture of 3′-PO4 and 3′-OH termini

2020 ◽  
Author(s):  
Shreya Ghosh ◽  
Anam Ejaz ◽  
Lucas Repeta ◽  
Stewart Shuman
Keyword(s):  
Pseudomonas Putida ◽  
Bound Water ◽  
Acid Catalyst ◽  
Nuclease Activity ◽  
Single Strand ◽  
Dna Endonuclease ◽  
Dependent Endonuclease ◽  
Leaving Group ◽  
Phosphodiester Hydrolysis ◽  
Hydrolysis Of

Abstract Pseudomonas putida MPE exemplifies a novel clade of manganese-dependent single-strand DNA endonuclease within the binuclear metallophosphoesterase superfamily. MPE is encoded within a widely conserved DNA repair operon. Via structure-guided mutagenesis, we identify His113 and His81 as essential for DNA nuclease activity, albeit inessential for hydrolysis of bis-p-nitrophenylphosphate. We propose that His113 contacts the scissile phosphodiester and serves as a general acid catalyst to expel the OH leaving group of the product strand. We find that MPE cleaves the 3′ and 5′ single-strands of tailed duplex DNAs and that MPE can sense and incise duplexes at sites of short mismatch bulges and opposite a nick. We show that MPE is an ambidextrous phosphodiesterase capable of hydrolyzing the ssDNA backbone in either orientation to generate a mixture of 3′-OH and 3′-PO4 cleavage products. The directionality of phosphodiester hydrolysis is dictated by the orientation of the water nucleophile vis-à-vis the OH leaving group, which must be near apical for the reaction to proceed. We propose that the MPE active site and metal-bound water nucleophile are invariant and the enzyme can bind the ssDNA productively in opposite orientations.

Metal complex catalyzed reactions of anils. III. Kinetic and mechanistic studies

1977 ◽  
Vol 55 (12) ◽  
pp. 2432-2441 ◽  
Author(s):  
A. R. Boate ◽  
D. R. Eaton
Keyword(s):  
Aqueous Solution ◽  
Metal Complex ◽  
Metal Atom ◽  
Nucleophilic Attack ◽  
Mechanistic Studies ◽  
Acetone Molecule ◽  
Rate Determining Step ◽  
Catalyzed Reactions ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of the homogeneously catalyzed formation and hydrolysis of anils in non-aqueous solution have been studied. The catalysts used are zinc complexes of thiourea. It is shown that all the evidence obtained, kinetic and otherwise, is consistent with a model in which the rate determining step for anil formation is nucleophilic attack by an aniline held in the second coordination sphere of the metal complex on an acetone molecule directly bound to the metal atom. Analogous mechanisms are suggested for anil hydrolysis and for transimination.

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