Carlsson A E
Department of Physics, Washington University, St Louis, MO 63130, USA.
Phys Biol. 2008 Jul 14;5(3):036002. doi: 10.1088/1478-3975/5/3/036002.
The effects of hydrolysis of ATP-actin to ADP-actin on actin polymerization-based force generation are calculated using a multifilament two-state Brownian ratchet model. The model treats an ensemble of rigid parallel filaments growing against a hard, inert, diffusing obstacle held in an optical trap. The filaments stochastically grow, depolymerize and undergo transitions between polymerizing and depolymerizing tip states. The parameters in the model are obtained from literature values and a fit to the measured dependence of the polymerization rate on the free-actin concentration. For more than two filaments, the stall force per filament near the critical concentration is much less than the equilibrium ATP-actin stall force. By reducing the availability of free monomers, the obstacle causes filament tips to convert to the depolymerizing state, so that only a small fraction of the filaments contact the obstacle at a given time.
利用多丝双态布朗棘轮模型计算了ATP -肌动蛋白水解为ADP -肌动蛋白对基于肌动蛋白聚合的力产生的影响。该模型处理一组刚性平行细丝，这些细丝在光学陷阱中对抗一个坚硬、惰性、扩散的障碍物生长。细丝随机生长、解聚，并在聚合和解聚的尖端状态之间转换。模型中的参数取自文献值，并拟合了聚合速率对游离肌动蛋白浓度的测量依赖性。对于多于两根细丝的情况，临界浓度附近每根细丝的失速力远小于平衡ATP -肌动蛋白失速力。通过减少游离单体的可用性，障碍物会使细丝尖端转变为解聚状态，从而在给定时间只有一小部分细丝与障碍物接触。
