sup 31 P ENDOR studies of xanthine oxidase: Coupling of phosphorus of the pterin cofactor to molybdenum(V)

Journal Article · Tue Apr 23 04:00:00 EDT 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00230a024· OSTI ID:5594973

Howes, B D; Bennett, B; Koppenhoefer, A; Lowe, D J; Bray, R C ^[1]

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1. Univ. of Sussex, Brighton (England)

{sup 31}P 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. 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{angstrom}. This implies that the cofactor is in an extended conformation in the enzyme molecule. Less detailed {sup 31}P ENDOR data on sulfite oxidase are consistent with a similar conformation for the cofactor in this enzyme.

• OSTI ID: 5594973
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 30:16; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ANISOTROPY
AROMATICS
AZAARENES
CHEMICAL SHIFT
COENZYMES
ENDOR
ENZYMES
HETEROCYCLIC COMPOUNDS
HYPERFINE STRUCTURE
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MOLYBDENUM COMPOUNDS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDOREDUCTASES
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
PTERIDINES
PURINES
REFRACTORY METAL COMPOUNDS
RESONANCE
STABLE ISOTOPES
TRANSITION ELEMENT COMPOUNDS
XANTHINES