Baracca A, Barogi S, Gabellieri E, Lenaz G, Solaini G
Dipartimento di Biochimica G. Moruzzi, Università di Bologna, Italy.
Biochem Biophys Res Commun. 1995 Feb 6;207(1):369-74. doi: 10.1006/bbrc.1995.1197.
The bovine heart mitochondrial F1-ATPase complex exhibits an intrinsic tryptophan phosphorescence that can be used to monitor structural changes of the epsilon-subunit. The phosphorescence decay rate of F1 containing the tightly bound nucleotides increases upon addition of adenine nucleoside triphosphate in the presence of magnesium. The average phosphorescence lifetime of this enzyme preparation decreases from 10.2 to 7.8 ms upon Mg-ATP addition. Since increasing phosphorescence decay rate is related to increasing flexibility of proteins, Mg-ATP added to the F1-ATPase complex can enhance the flexibility of the protein structure surrounding the chromophore. Experiments carried out on F1 prepared with the three noncatalytic sites filled and the three catalytic sites vacant show a significant increase of the phosphorescence lifetime from 6.4 ms to 7.6 ms upon Mg-ATP addition. These results suggest that the mitochondrial F1-ATPase epsilon-subunit conformation senses differently the nucleoside triphosphate binding to catalytic or noncatalytic sites.
牛心线粒体F1 - ATP酶复合体表现出一种内在的色氨酸磷光，可用于监测ε亚基的结构变化。在镁存在的情况下，添加三磷酸腺苷时，含有紧密结合核苷酸的F1的磷光衰减速率会增加。添加Mg - ATP后，这种酶制剂的平均磷光寿命从10.2毫秒降至7.8毫秒。由于磷光衰减速率增加与蛋白质柔韧性增加有关，添加到F1 - ATP酶复合体中的Mg - ATP可以增强发色团周围蛋白质结构的柔韧性。在用三个非催化位点填充且三个催化位点空缺制备的F1上进行的实验表明，添加Mg - ATP后，磷光寿命从6.4毫秒显著增加到7.6毫秒。这些结果表明，线粒体F1 - ATP酶ε亚基构象对与催化或非催化位点结合的三磷酸核苷的感知不同。
