Piatt J, O'Brien P J
Eur J Biochem. 1979 Jan 15;93(2):323-32. doi: 10.1111/j.1432-1033.1979.tb12826.x.
Evidence for singlet oxygen formation has been obtained for the lactoperoxidase, H2O2 and bromide system by monitoring 2,3-diphenylfuran and diphenylisobenzofuran oxidation, O2 evolution, and chemiluminescence. This could provide an explanation for the cytotoxic and microbicidal activity of peroxidases and polymorphonuclear leukocytes. Evidence for singlet oxygen formation included the following. (a) Chemiluminescence accompanying the enzymic reaction was doubled in a deuterated buffer and inhibited by singlet oxygen traps. (b) The singlet oxygen traps, diphenylfuran and diphenylisobenzofuran, were oxidized to their known singlet oxygen oxidation products in the presence of lactoperoxidase, hydrogen peroxide and bromide. (c) The rate of oxidation of diphenylfuran and diphenylisobenzofuran was inhibited when monitored in the presence of known singlet oxygen traps or quenchers. (d) Oxygen evolution from the enzymic reaction was inhibited by singlet oxygen traps but not by singlet oxygen quenchers. (e) The traps or quenchers which were effective inhibitors in the experiments above did not inhibit peroxidase activity, were not competitive peroxidase substrates and did not react with the hypobromite intermediate since they did not inhibit hydrogen peroxide consumption by the enzyme. Using these criteria, various biological molecules were tested for their reactivity with singlet oxygen. Furthermore, by studying their effect on oxygen release by the enzymic reaction, it could be ascertained whether they were acting as singlet oxygen traps or quenchers.
通过监测2,3 - 二苯基呋喃和二苯基异苯并呋喃的氧化、氧气释放以及化学发光，已获得了关于乳过氧化物酶、过氧化氢和溴化物体系中单线态氧形成的证据。这可以解释过氧化物酶和多形核白细胞的细胞毒性和杀菌活性。单线态氧形成的证据如下：(a) 在氘代缓冲液中，酶促反应伴随的化学发光增强了一倍，并被单线态氧陷阱抑制。(b) 在乳过氧化物酶、过氧化氢和溴化物存在的情况下，单线态氧陷阱二苯基呋喃和二苯基异苯并呋喃被氧化为其已知的单线态氧氧化产物。(c) 当在已知的单线态氧陷阱或猝灭剂存在下进行监测时，二苯基呋喃和二苯基异苯并呋喃的氧化速率受到抑制。(d) 酶促反应中的氧气释放被单线态氧陷阱抑制，但不被单线态氧猝灭剂抑制。(e) 在上述实验中作为有效抑制剂的陷阱或猝灭剂不抑制过氧化物酶活性，不是竞争性过氧化物酶底物，并且不与次溴酸盐中间体反应，因为它们不抑制该酶对过氧化氢的消耗。使用这些标准，测试了各种生物分子与单线态氧的反应性。此外，通过研究它们对酶促反应中氧气释放的影响，可以确定它们是作为单线态氧陷阱还是猝灭剂起作用。
