Hackney D D, Rosen G, Boyer P D
Proc Natl Acad Sci U S A. 1979 Aug;76(8):3646-50. doi: 10.1073/pnas.76.8.3646.
Pronounced substrate modulation of incorporation of water oxygen into ATP formed by photophosphorylation is observed, as measured by 31P NMR analysis of products formed from ADP and highly 18O-labeled Pi. A marked increase occurs in oxygen exchange per ATP formed as ADP or Pi concentration is decreased. This is explainable by the binding-change mechanism for ATP synthesis, in which the energy-linked release of ATP from one site requires the binding of ADP and Pi at an alternate site. Analysis of the distribution of 18O-labeled species arising from the ATP formed eliminates explanations for substrate modulation based on preexisting or induced enzyme heterogeneity. Furthermore, the results, together with other related findings, make participation of control sites unlikely. The occurrence of alternating site catalysis cooperativity in ATP synthesis by chloroplasts thus appears to be reasonably well established.
通过对由ADP和高18O标记的Pi形成的产物进行31P NMR分析，观察到光磷酸化形成的ATP中，水氧掺入存在明显的底物调节现象。随着ADP或Pi浓度降低，每形成一个ATP的氧交换显著增加。这可以用ATP合成的结合变化机制来解释，即从一个位点能量偶联释放ATP需要在另一个位点结合ADP和Pi。对形成的ATP中18O标记物种分布的分析排除了基于预先存在或诱导的酶异质性对底物调节的解释。此外，这些结果与其他相关发现一起，使得控制位点参与的可能性不大。因此，叶绿体ATP合成中交替位点催化协同性的存在似乎已得到合理的确立。
