Abstract
Xanthine dehydrogenase (XDH) is an important precursor to the oxygen radical producing enzyme xanthine oxidase (XO). We found that the apparent activity of rabbit myocardial XDH increased from 2 ± 1 to 50 ± 3 μU/g (P<0.05) following extraction of tissue homogenate with butanol. Further studies suggested that the basis for this observation was a high molecular weight compound which consumes the XDH cofactor, NAD+. Addition of myocardial homogenate to exogenous NAD+ resulted in depletion of NAD+ and concomitant formation of an additional compound (peak A). Both NAD+ consumption and peak A formation were abrogated by prior extraction of homogenate with butanol. Separation of myocardial homogenate by Sephadex chromatography revealed a high molecular weight compound which suppressed activity of purified milk XDH but not xanthine oxidase (XO). This activity co-eluted with the ability of myocardial homogenate to consume added NAD+ and form peak A. The NAD+-consuming activity was heat and acid-labile. In addition, nicotinamide was both a product and an inhibitor of the NADase activity, consistent with the existence of a previously described myocardial glycohydrolase. Extraction of tissue with butanol may be necessary to detect low levels of XDH activity in vitro.
Original language | English (US) |
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Pages (from-to) | 125-132 |
Number of pages | 8 |
Journal | Journal of Molecular and Cellular Cardiology |
Volume | 26 |
Issue number | 2 |
DOIs | |
State | Published - Feb 1994 |
Keywords
- 1-butanol
- Glycohydrolase
- HPLC
- Ischemia-reperfusion
- Nicotinamide adenine dinucleotide
- Xanthine oxidase
ASJC Scopus subject areas
- Molecular Biology
- Cardiology and Cardiovascular Medicine