Certain oximes form nitric oxide upon reaction with 4-phenyl-1,2,4-triazole-3,5-dione (PTAD). The oximes appear to undergo an Alder-ene reaction with the PTAD enophile to form a nitroso intermediate capable of dimerization and/or nitric oxide formation. Upon exposure to oxygen, the nitroso compounds eventually form ketones. This reaction may serve as a model for the study of nitric oxide synthase (NOS), the enzyme responsible for physiological production of nitric oxide. NOS is known to produce an oxime intermediate which reacts with oxygen to produce nitric oxide and citrulline.

中文翻译：

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肟与4-苯基-1,2,4-三唑啉-3,5-二酮的反应生成一氧化氮–一氧化氮合酶的模型化合物

某些肟与4-苯基-1,2,4-三唑-3,5-二酮（PTAD）反应形成一氧化氮。肟似乎与PTAD亲有机物发生Alder-ene反应，形成能够二聚和/或形成一氧化氮的亚硝基中间体。暴露于氧气后，亚硝基化合物最终形成酮。该反应可作为研究一氧化氮合酶（NOS）的模型，该酶负责生理产生一氧化氮。已知NOS产生肟中间体，该肟中间体与氧反应产生一氧化氮和瓜氨酸。