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IJC-A Vol.49A(08) [August 2010] >


Title: Structure-function mimicry of oxidized purple acid phosphatase-PAPox – A new functional model
Authors: Waghmode, Shobha A
Date, Sadgopal K
Gupta, Vidya S
Rane, Sandhya Y
Keywords: Bioinorganic chemistry
Nuclease activity
PAPox analogues
Iron
DNA cleavage
Antiferromagnetic exchange
Issue Date: Aug-2010
Publisher: CSIR
IPC CodeInt. Cl.9 C07F15/02
Abstract: Electronic structure and spectroscopic properties of the novel diiron active site of oxidized mammalian purple acid phosphatase analogues, Fe-6: [Fe2 ( -O) ( -OAc) (4HNSQox)(ONSQox)2(H2O)4] and Fe-7: [Fe2 ( -O) ( -OAc)(ONSQox)2(OAc) (H2O)4] are described. Magnetic susceptibility SQUID data of Fe-6 are best fitted to Heisenberg’s isotropic spin pair (S = 5/2, 3/2) model using magnetic parameters g = 2 and J = – 36.8 cm-1 with R factor = 6.4 × 10-4. The antiferromagnetic exchange establishes Fe(III)-O-Fe(III) dimeric core with Fe(III) site having two radical ligations in the naphthosemiquinone oxime form of lawsone oxime. In the model compound Fe-7 of oxidized purple acid phosphatase, bridged and terminal acetate functions are identified according to their different energies of activations, i.e, ~34 and 58 kJ mol-1 respectively. Also, the reduced naphthoquinone oxime form of ligand is characterized by its energy of activation (~15 kJ mol-1) from pyrolytic reaction. Mössbauer parameters, = 0.4 mm s-1 and DEQ = 0.8 mm s-1, are characteristics of oxidized Fe(III) in high spin octahedral site. Only Fe-6 shows analogous physiological DNA cleavage activity on pUC19 plasmid and acts as a good model of oxidized purple acid phosphatase enzyme.
Page(s): 1023-1029
Source:IJC-A Vol.49A(08) [August 2010]

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