Department of Sciences of Life and Environment, University of Cagliari, I-09042 Monserrato, Cagliari, Italy.
FEBS Open Bio. 2012 Sep 29;2:305-12. doi: 10.1016/j.fob.2012.09.004. Print 2012.
The oxidation of nitric oxide (NO) by Euphorbia characias latex peroxidase (ELP-Fe(III)), in the presence or in the absence of added calcium, has been investigated. The addition of hydrogen peroxide to the native enzyme leads to the formation of Compound I and serves to catalyse the NO oxidation. The addition of NO to Compound I leads to the formation of Compound II and, afterwards, to the native enzyme spectrum. Under anaerobic conditions, the incubation of the native enzyme (ELP-Fe(III))with NO leads to the formation of the stable complex, showing a characteristic absorption spectrum (ELP-Fe(II)-NO(+)). The rate of the formation of this complex is slower in the presence of calcium than in its absence, and the same applies to the rate of the formation of Compound II from Compound I, using NO as substrate. Finally, we demonstrate that NO protects ELP from the inactivation caused by CN(-) via a mechanism presumably requiring the formation of an enzyme-nitrosyl cyanide complex.
辣根过氧化物酶（Euphorbia characias latex peroxidase，ELP-Fe(III)）存在或不存在外加钙的情况下，催化一氧化氮（NO）的氧化。向天然酶中添加过氧化氢会形成化合物 I，并催化 NO 氧化。向化合物 I 中添加 NO 会形成化合物 II，随后形成天然酶光谱。在厌氧条件下，将天然酶（ELP-Fe(III)）与 NO 孵育会形成稳定的复合物，显示出特征吸收光谱（ELP-Fe(II)-NO(+))。在存在钙的情况下，该复合物的形成速度比不存在钙时慢，而以 NO 为底物从化合物 I 形成化合物 II 的速度也是如此。最后，我们证明 NO 通过一种可能需要形成酶-亚硝酰氰化物复合物的机制来保护 ELP 免受 CN(-)引起的失活。
