xanthine + formaldehyde + NAD(+) + H2O => 7-methylxanthine + NADH + O2 + H(+)
xanthine + formaldehyde + nad(+) + h2o => 7-methylxanthine + nadh + o2 + h(+)
xanthine + formaldehyde + NAD(+) + H2O => 7-methylxanthine + NADH + O2 + H(+)
xanthine + formaldehyde + nad(+) + h2o => 7-methylxanthine + nadh + o2 + h(+)