叠氮活化烟草多酚氧化酶II的机理

至今人们一直报道叠氮作为金属蛋白 (特别是铜蛋白 )的一种抑制剂 ,本研究表明叠氮也可以作为烟草多酚氧化酶 II(简称PPOII)的激活剂。在天然 PPOII、叠氮 - PPOII络合物和过氧化物 - PPOII络合物的方波电位学研究中 ,从硝基蓝四唑 (nitro bluetetrazolium)能被酶还原和 PPOII能被过氧化物激活的试验结果可以看出 ,叠氮与 PPOII的结合诱导了天然 PPOII活性中心的Cu O2 - Cu生成了 Cu O2 2 - Cu活性中心结构。叠氮作为激活剂的原因应归因于叠氮分子与 PPOII的络合反应导致了 Cu O2 2 - Cu的生成 ,它恰是过氧化物 - PPOII络合物的活性中心 ,其实质是过氧负离子起到激活剂的作用。

The mechanism of azide activating polyphenol oxidase II in tobacco

Azide has been consistently reported to act as an inhibitor of metal enzymes,especially copper proteins.The present work shows that azide can also act as activator of polyphenol oxidase II (PPOII) in tobacco leaves. From the square-wave voltammetry of native PPOII, peroxide- PPOII complex and azide-PPOII complex, the reduction of nitro blue tetrazolium by the enzymes and activation of PPOII by peroxide it follows that the binding of azide to PPOII induces the formation of CuO 2 2-Cu in the active site of PPOII from CuO 2-Cu in native PPOII. The reason for azide acting as activator can be attributed to azide complexing with PPOII,thus inducing the formation of CuO 2 2-Cu,which is the active site of the peroxide- PPOII complex in which peroxide plays the role of activator.