Sinjorgo K M, Durak I, Dekker H L, Edel C M, Bieleman A H, Back N B, Hakvoort T B, Muijsers A O
Biochim Biophys Acta. 1987 Sep 10;893(2):241-50. doi: 10.1016/0005-2728(87)90045-4.
(1) Investigation of the relationship between the detergent concentration and steady-state and pre-steady-state kinetics of cytochrome c oxidase proved to be a valid approach in the study of protein-detergent interaction. (2) Laurylmaltoside, sodium cholate and Triton X-100 influenced the kinetics of cytochrome c oxidase cooperatively at detergent concentrations near their critical micelle concentration. This mode of interaction reflects disaggregation of the oxidase as a result of cooperative binding of the detergent. (3) Addition of increasing concentrations of Tween-80 to the aggregated enzyme caused a more gradual decrease in aggregation of the oxidase, which did not result in a change in activity of the enzyme. This suggests that aggregation of cytochrome c oxidase occurs in a highly regular manner in which no catalytic sites are shielded off. (4) Oxidase aggregates present at detergent concentrations below the critical micelle concentration of laurylmaltoside and Triton X-100 showed considerable activity. Their kinetics were equal to those of the oxidase in Tween-80, suggesting that the protein molecules are aligned in a similar way in all oligomers. Aggregates present in low concentrations of sodium cholate showed turnover rates that were twice as low as those observed with other aggregates. (5) Solubilisation of the oxidase by sodium cholate or Triton X-100 resulted in almost complete inhibition of enzymic activity, whereas the association rate of ferrocytochrome c was almost equal to that found for monomeric oxidase in laurylmaltoside. These results are in agreement with a mixed-type inhibition.
(1) 研究洗涤剂浓度与细胞色素c氧化酶的稳态和预稳态动力学之间的关系，被证明是研究蛋白质 - 洗涤剂相互作用的一种有效方法。(2) 月桂基麦芽糖苷、胆酸钠和 Triton X - 100 在接近其临界胶束浓度的洗涤剂浓度下协同影响细胞色素c氧化酶的动力学。这种相互作用模式反映了由于洗涤剂的协同结合导致氧化酶的解聚。(3) 向聚集的酶中添加浓度不断增加的吐温 - 80 会使氧化酶的聚集逐渐减少，但这并未导致酶活性的改变。这表明细胞色素c氧化酶的聚集以高度规则的方式发生，其中没有催化位点被屏蔽。(4) 在低于月桂基麦芽糖苷和 Triton X - 100 的临界胶束浓度的洗涤剂浓度下存在的氧化酶聚集体具有相当的活性。它们的动力学与吐温 - 80 中的氧化酶的动力学相同，表明蛋白质分子在所有寡聚体中以相似的方式排列。低浓度胆酸钠中存在的聚集体的周转速率是其他聚集体观察到的周转速率的一半。(5) 用胆酸钠或 Triton X - 100 溶解氧化酶几乎完全抑制了酶活性，而亚铁细胞色素c的缔合速率几乎与月桂基麦芽糖苷中单体氧化酶的缔合速率相等。这些结果与混合型抑制一致。
