xanthine + H2O + NAD+ => urate + NADH + H+ (Gallus gallus)
xanthine + h2o + nad+ => urate + nadh + h+ (gallus gallus)
xanthine + H2O + NAD+ => urate + NADH + H+ (Gallus gallus)
xanthine + h2o + nad+ => urate + nadh + h+ (gallus gallus)