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Purification and characterization of mouse liver xanthine oxidase

G Carpani1, M Racchi, P Ghezzi

  • 1Molecular Biology Unit, Centro Daniela e Catullo Borgomainerio, Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.

Archives of Biochemistry and Biophysics
|June 1, 1990
PubMed

Insights

Researchers purified mouse liver xanthine oxidase (XO) after bacterial lipopolysaccharide induction. This study characterizes the enzyme

Area of Science:

  • Biochemistry
  • Enzymology
  • Molecular Biology

Background:

  • Xanthine oxidase (EC 1.1.3.22) is a key enzyme in purine metabolism.
  • Investigating enzyme properties aids understanding of metabolic pathways and potential therapeutic targets.

Purpose of the Study:

  • To purify and characterize xanthine oxidase (XO) from mouse liver following induction.
  • To determine the molecular weight, subunit composition, isoelectric point, and kinetic parameters of mouse XO.

Main Methods:

  • Enzyme purification to homogeneity from induced mouse liver.
  • Determination of native molecular weight and subunit composition via gel electrophoresis.
  • Isoelectric focusing to determine the isoelectric point.
  • Enzyme kinetics assays to determine Km for xanthine.

Main Results:

  • Xanthine oxidase was purified to homogeneity.
  • The native enzyme has an apparent molecular weight of 300,000 Da, composed of two identical subunits of 150,000 Da each.
  • The isoelectric point was determined to be 6.7.
  • The apparent Km for xanthine was found to be 3.4 microM.
  • Amino acid composition showed similarity to Drosophila xanthine dehydrogenase.

Conclusions:

  • Mouse liver xanthine oxidase is a homodimer with specific biochemical properties.
  • The characterized properties provide a basis for further functional and structural studies.
  • Observed similarities in amino acid composition suggest evolutionary conservation.

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