Le Bihan T, Gicquaud C
Département de Chimie-Biologie, Université du Québec à Trois-Rivières, Canada.
Biochem Biophys Res Commun. 1991 Dec 16;181(2):542-7. doi: 10.1016/0006-291x(91)91223-y.
We have used differential scanning calorimetry to study the effects of phalloidin on F and G actin stability. For F actin, saturating concentrations of phalloidin induced an important shift on the transition temperature, Tm, from 69.5 degrees C to 83.5 degrees C. However, the calorimetric enthalpy remained unchanged. Using lower phalloidin concentrations, monomers linked to phalloidin, as well as neighboring unlinked monomers, were both stabilized. Contrary to previous reports, phalloidin was also shown to affect G actin, shifting its Tm from 59.5 degrees C to 75 degrees C. Two mechanisms are proposed to explain this finding: first, it could indicate a real interaction of phalloidin with G actin, and second, heating of the specimen during the scan could have induced polymerization of some G actin to the F form. The resulting F polymer would then interact with phalloidin, thus shifting the equilibrium between G and F actin towards the polymeric form.
我们使用差示扫描量热法研究了鬼笔环肽对F-肌动蛋白和G-肌动蛋白稳定性的影响。对于F-肌动蛋白，饱和浓度的鬼笔环肽使转变温度Tm发生了显著变化，从69.5℃变为83.5℃。然而，量热焓保持不变。使用较低浓度的鬼笔环肽时，与鬼笔环肽相连的单体以及相邻的未相连单体均得到稳定。与之前的报道相反，鬼笔环肽也被证明会影响G-肌动蛋白，将其Tm从59.5℃变为75℃。提出了两种机制来解释这一发现：第一，这可能表明鬼笔环肽与G-肌动蛋白存在真实的相互作用；第二，扫描过程中样品受热可能诱导一些G-肌动蛋白聚合成F-形式。生成的F-聚合物随后会与鬼笔环肽相互作用，从而使G-肌动蛋白和F-肌动蛋白之间的平衡向聚合形式移动。
