A Purple Acid Phosphatase from Sweet Potato Contains an Antiferromagnetically Coupled Binuclear Fe-Mn Center

Schenk, Gerhard and Boutchards, Clare and Carrington, Lyle E. and Noble, Christopher J. and Moubaraki, Boujemaa and Murray, Keith S. and de Jersey, John and Hanson, Graeme R. and Hamilton, Susan E. (2001) A Purple Acid Phosphatase from Sweet Potato Contains an Antiferromagnetically Coupled Binuclear Fe-Mn Center. Biochemistry, 276 (22). pp. 19084-19088. ISSN 0006-2960

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A purple acid phosphatase from sweet potato is the first reported example of a protein containing an enzymatically active binuclear Fe-Mn center. Multifield saturation magnetization data over a temperature range of 2 to 200 K indicates that this center is strongly antiferromagnetically coupled. Metal ion analysis shows an excess of iron over manganese. Low temperature EPR spectra reveal only resonances characteristic of high spin Fe(III) centers (Fe(III)-apo and Fe(III)-Zn(II)) and adventitious Cu(II) centers. There were no resonances from either Mn(II) or binuclear Fe-Mn centers. Together with a comparison of spectral properties and sequence homologies between known purple acid phosphatases, the enzymatic and spectroscopic data strongly indicate the presence of catalytic Fe(III)-Mn(II) centers in the active site of the sweet potato enzyme. Because of the strong antiferromagnetism it is likely that the metal ions in the sweet potato enzyme are linked via a m-oxo bridge, in contrast to other known purple acid phosphatases in which a m-hydroxo bridge is present. Differences in metal ion composition and bridging may affect substrate specificities leading to the biological function of different purple acid phosphatases.

Item Type: Article
Keywords: Purple Acid Phosphatase; Sweet Potato; Antiferromagnetically Coupled Binuclear Fe-Mn Center;
Academic Unit: Faculty of Science and Engineering > Chemistry
Item ID: 3706
Depositing User: Gary Schenk
Date Deposited: 30 May 2012 09:16
Journal or Publication Title: Biochemistry
Publisher: American Chemical Society
Refereed: Yes

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