NITRIC OXIDE SYNTHESIS CAPABILITIES OF CYTOCHROME P450 1A2 AND NADPH-CYTOCHROME P450 REDUCTASE FROM NG-HYDROXY-L-ARGININE
NO was formed from NG-hydroxy-L-arginine by cytochrome P450 1A2 (P450 1A2) with turnover numbers of 0.6 - 1.2 nmol/nmolP450/min and 62 pmol/nmolP450/min in peroxide-supported shunt and reconstituted systems, respectively. A Glu318Ala mutation of P450 1A2 enhanced the shunt-reaction activity up to 7.3-fold, whereas the mutation abolished the activity with the reconstituted system. Involvement of H2O2 or superoxide anion in the NO synthesis is also suggested.