Hawkesford M J, Reed R H, Rowell P, Stewart W D
Eur J Biochem. 1982 Sep;127(1):63-6. doi: 10.1111/j.1432-1033.1982.tb06837.x.
The relationships between nitrogenase activity (acetylene reduction) and the transplasmalemma proton electrochemical potential gradient (delta muH+) have been investigated using the non-heterocystous filamentous cyanobacterium Plectonema boryanum. By selectively modifying the chemical (delta pH) and electrical (delta psi) components of delta muH+ under conditions in which the size of the ATP pool remained unaffected, nitrogenase activity was found to be dependent on, or regulated by delta psi. When the ATP pool decreased, concomitant with a decreased internal pH (pHi) the requirement for delta psi was modified. The observed reduction in the intracellular ATP pool and the decreased ATP:ADP ratio also correlated with an inhibition of nitrogenase activity. The data are consistent with a model in vivo in which reductant supply to nitrogenase is regulated by, or dependent on an energised plasmalemma and where there is a fine balance between the supply of reductant and ATP for nitrogenase activity. The correlation observed between delta psi and nitrogenase activity extends our previous observations using the heterocystous cyanobacterium Anabaena variabilis.
利用非异形丝状蓝细菌鞘丝藻，研究了固氮酶活性（乙炔还原）与跨质膜质子电化学势梯度（δμH⁺）之间的关系。在ATP库大小不受影响的条件下，通过选择性改变δμH⁺的化学（δpH）和电（δψ）组分，发现固氮酶活性依赖于或受δψ调节。当ATP库减少时，伴随着细胞内pH（pHi）降低，对δψ的需求也发生改变。观察到的细胞内ATP库减少以及ATP:ADP比值降低也与固氮酶活性的抑制相关。这些数据与体内模型一致，在该模型中，向固氮酶的还原剂供应受有能量的质膜调节或依赖于有能量的质膜，并且在为固氮酶活性提供还原剂和ATP之间存在精细平衡。观察到的δψ与固氮酶活性之间的相关性扩展了我们之前使用异形蓝细菌多变鱼腥藻的观察结果。
