[中文摘要]根据配位催化原理和化学探针思路，推断了野生菌固氮酶在酶促固氮反应中[Ｍｏ]位直接参与结合分子氮Ｎ≡Ｎ；论证了固氮酶钼铁蛋白的Ｍ－簇（Ｋｉｍ－Ｒｅｅｓ模型）必须是活口的钼－铁－硫原子簇笼，对底物和抑制剂有分子识别能力，只有Ｎ≡Ｎ才能作为底物络合在［Ｍｏ－３Ｆｅ，３Ｆｅ］七核活性中心，而且必须有一条质子（和电子）接力传递链到达［Ｍｏ］位，Ｎ≡Ｎ才能排去氢基配体而进到［Ｍｏ］位，（否则就只能象那样结合在［６Ｆｅ］位）：此外还需要另一条质子接力传递链进到［Ｆｅ２］位才能使Ｎ≡Ｎ从外端Ｎ逐步还原加氢．其它十多种底物分子按形状和大小，只能在笼内［６Ｆｅ］应，或笼口［２Ｆｅ］位，或一部份在笼内、一部份在笼外还原加氢，这些底物只需要两条质子接力传递链中有一条不失效就行．阐明了ＣＯ不是底物而是所有外源底物酶促还原反应的抑制剂的原因．讨论了两条质子接力传递链及其支架基团的本质和进一步验证的方法．设计了一种基于其它底物或抑制剂对ＣＨ≡ＣＨ酶促还原加氘的竞争抑制来检验它们是在笼内或笼外结合的化学探针方法，并成功地用于验证高柠檬酸盐固氮酶确是在笼内强烈地抑制乙炔还原加氘（氢）的．[英文摘要]Based upon the principles of coordination catalysis and chemical approach, it has been inferred that in active, native nitrogenase, [Mo] directly takes part in binding dinitrogen,Ｎ≡Ｎ， and that the M-cluster of Kim-Rees-Chan Model must be a labile-mouthed cluster cage with molecular recognition in the bindings of substrates and inhibitors; the [Mo]-site of the [Mo-3Fe, 3Fe]active center being available only to N三N，μ7-coordination and only when there is a proton (and electron) relay pathway from the P-cluster pair to the [Mo〕-site;andaseeond proton relay pathway is required for the reduetion of the μ7-（η2,ε4,ε3’）coordinatively bonded Ｎ≡Ｎ,and that other substrates,according to molecular sizes and shapes,are bound at the [6Fe]-site inside the cage,or at the [2Fe]-site of the gape,while CO is most probably bound at the [4Fe]-site inside the cage and at the [2Fe]-site of the gape,thus not inhibition H2 evolution from the [Mo-Fe7]-site.The nature of the two proton-relay pathways and their supporting groups is discussed.A chemical-probe method has been designed,based upon inhibtion of HC≡CH reductive-deuteration by other substrates or inhibitors and the effects on trans-/cis-d2-ethene ratios,for examining the binding sites of these substrates or inhibitors (whether inside the cage,or outside the cage),and the strength of binding; this method has been successfully used in obtaining strong support for the strong competitive bonding of Ｎ≡Ｎ vs.HC≡CH inside the cage,but pactically no inhibition of HC≡CH by Ｎ≡Ｎ at the [2Fe]-site of thegape.国家科委攀登计划共生固氮课题，国家自然科学基
