Faculty Collaboration Database

31P ENDOR studies of xanthine oxidase: coupling of phosphorus of the pterin cofactor to molybdenum (V). Biochemistry 1991 Apr 23;30(16):3969-75

Date

04/23/1991

Pubmed ID

1850296

DOI

10.1021/bi00230a024

Scopus ID

2-s2.0-0025922525 (requires institutional sign-in at Scopus site)   22 Citations

Abstract

31P ENDOR spectra are described for three different molybdenum(V) species in reduced xanthine oxidase samples. The spectra were not affected by removing the FAD from the enzyme, implying that this is located at some distance from molybdenum. Furthermore, in confirmation of the work of J. L. Johnson, R. E. London, and K. V. Rajagopalan [(1989) Proc. Natl. Acad. Sci. U.S.A. 86, 6493-6497], NMR and chemical analysis of the phosphate content of highly purified xanthine oxidase showed there are only three phosphate residues per subunit of the enzyme. It is concluded that the ENDOR features are due to hyperfine coupling of the phosphate group of the pterin cofactor to the molybdenum atom. Evaluation of the dipolar component of the coupling has permitted estimation of the molybdenum-phosphorus distances as 7-12 A. This implies that the cofactor is in an extended conformation in the enzyme molecule. Less detailed 31P ENDOR data on sulfite oxidase are consistent with a similar conformation for the cofactor in this enzyme.

Author List

Howes BD, Bennett B, Koppenhöfer A, Lowe DJ, Bray RC

Author

Brian Bennett D.Phil. Professor and Chair in the Physics department at Marquette University

MESH terms used to index this publication - Major topics in bold

Animals
Cattle
Coenzymes
Electron Spin Resonance Spectroscopy
Female
Hydrogen-Ion Concentration
Kinetics
Magnetic Resonance Spectroscopy
Metalloproteins
Milk
Molybdenum
Phosphorus
Protein Binding
Pteridines
Xanthine Oxidase