31P ENDOR Studies of Xanthine Oxidase: Coupling of Phosphorus of the Pterin Cofactor to Molybdenum(V)
Document Type
Article
Language
eng
Format of Original
7 p.
Publication Date
4-1991
Publisher
American Chemical Society
Source Publication
Biochemistry
Source ISSN
0006-2960
Original Item ID
doi: 10.1021/bi00230a024
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 Å. 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.
Recommended Citation
Howes, Barry D.; Bennett, Brian; Koppenhofer, Alrik; Lowe, David J.; and Bray, Robert C., "31P ENDOR Studies of Xanthine Oxidase: Coupling of Phosphorus of the Pterin Cofactor to Molybdenum(V)" (1991). Physics Faculty Research and Publications. 63.
https://epublications.marquette.edu/physics_fac/63
Comments
Biochemistry, Vol. 30, No. 16 (April 1991): 3969-3975. DOI.
Brian Bennett was affiliated with University of Sussex at the time of publication.