CROSS-LINKER DYNAMICS DETERMINE THE MECHANICAL-PROPERTIES OF ACTIN GELS
CROSS-LINKER DYNAMICS DETERMINE THE MECHANICAL-PROPERTIES OF ACTIN GELS
复制标题
DOI：
10.1016/s0006-3495(94)80856-2
复制
发表时间：
1994-03-01
影响因子：
3.4
通讯作者：
POLLARD, TD
中科院分区：
文献类型：
--
作者：
WACHSSTOCK, DH;SCHWARZ, WH;POLLARD, TD
为了评估交联剂动力学和聚合物变形对肌动蛋白丝凝胶频率依赖性刚度的贡献，我们比较了三种类型交联剂的肌动蛋白凝胶的流变学性质：弱交联剂，阿米巴α-辅肌动蛋白（解离速率常数5.2 s（-1），结合速率常数1.1 x 10（6）M（-1）s（-1））;一个强有力的，鸡平滑肌α-辅肌动蛋白（解离速率常数0.66 s（-1），结合速率常数1.20 × 10（6）M（-1）s（-1））;和一个非常强的，生物素/抗生物素蛋白（解离速率常数约为零）。生物素/抗生物素蛋白交联凝胶的行为仅由聚合物弯曲决定，其行为类似于固体并且不显示频率依赖性。变形虫α-辅肌动蛋白交联凝胶表现得像粘弹性流体，并且刚度的频率依赖性可以由动态交联凝胶的数学模型来解释。鸡α-辅肌动蛋白交联凝胶的刚度与频率无关，并且具有介于两者之间的粘弹性。这两种α-辅肌动蛋白具有相似的结合肌动蛋白丝的结合速率常数，与扩散限制反应一致。刚性交联使凝胶变硬，但使其具有弹性而不具有永久变形的能力。动态交联的肌动蛋白丝应该允许细胞被动地对各种外力做出反应，而不需要任何信号。较慢的信号介导途径，如切断细丝或改变交联剂的亲和力，可以改变这些被动反应的性质。
To evaluate the contributions of cross-linker dynamics and polymer deformation to the frequency-dependent stiffness of actin filament gels, we compared the rheological properties of actin gels with three types of cross-linkers: a weak one, Acanthamoeba alpha-actinin (dissociation rate constant 5.2 s(-1), association rate constant 1.1 x 10(6) M(-1) s(-1)); a strong one, chicken smooth muscle alpha-actinin (dissociation rate constant 0.66 s(-1), association rate constant 1.20 x 10(6) M(-1) s(-1)); and an extremely strong one, biotin/avidin (dissociation rate constant approximately zero). The biotin/avidin cross-linked gel, whose behavior is determined by polymer bending alone, behaves like a solid and shows no frequency dependence. The amoeba alpha-actinin cross-linked gel behaves like a viscoelastic fluid, and the frequency dependence of the stiffness can be explained by a mathematical model for dynamically cross-linked gels. The stiffness of the chicken alpha-actinin cross-linked gel is independent of frequency, and has viscoelastic properties intermediate between the two. The two alpha-actinins have similar association rate constants for binding to actin filaments, consistent with a diffusion-limited reaction. Rigid cross-links make the gel stiff, but make it elastic without the ability to deform permanently. Dynamically cross-linked actin filaments should allow the cell to react passively to various outside forces without any sort of signaling. Slower, signal-mediated pathways, such as severing filaments or changing the affinity of cross-linkers, could alter the nature of these passive reactions.