Adhikari S, Ray S, Gachhui R
Department of Biophysics, Molecular Biology and Genetics, University of Calcutta, 92, A.P.C. Road, 700009, Calcutta, India.
FEBS Lett. 2000 Jun 9;475(1):35-8. doi: 10.1016/s0014-5793(00)01616-1.
Nitric oxide synthases (NOSs) catalyze the formation of nitric oxide from L-arginine. We purified the heme containing, tetrahydrobiopterin-free, oxygenase domain of rat neuronal nitric oxide synthase (nNOSox) overexpressed in Escherichia coli. We found catalase activity in nNOSox. This is significant because H(2)O(2) may also be a product of nitric oxide synthases. We found H(2)O(2) assisted product formation from N-hydroxy-L-arginine and even from L-arginine both in the presence and in absence of tetrahydrobiopterin. We propose how heme moiety of the oxygenase domain alone is sufficient to carry out both steps of the NOS catalysis.
一氧化氮合酶（NOSs）催化L-精氨酸生成一氧化氮。我们纯化了在大肠杆菌中过表达的大鼠神经元一氧化氮合酶（nNOSox）的含血红素、无四氢生物蝶呤的加氧酶结构域。我们在nNOSox中发现了过氧化氢酶活性。这很重要，因为过氧化氢也可能是一氧化氮合酶的产物。我们发现，无论有无四氢生物蝶呤，过氧化氢都能促进从N-羟基-L-精氨酸甚至从L-精氨酸生成产物。我们提出了加氧酶结构域的血红素部分如何足以单独进行一氧化氮合酶催化的两个步骤。
