Dynamic properties of artificial protein hydrogels assembled through aggregation of leucine zipper peptide domains
Dynamic properties of artificial protein hydrogels assembled through aggregation of leucine zipper peptide domains
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DOI：
10.1021/ma0615194
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发表时间：
2007-02-06
期刊：
影响因子：
5.5
通讯作者：
Tirrell, David A.
中科院分区：
文献类型：
--
作者：
Shen, Wei;Kornfield, Julia A.;Tirrell, David A.
用剪切流变法研究了由基因工程多结构域蛋白（AC(10) a，其中a是结合亮氨酸拉链结构域，C-10是随机线圈聚电解质结构域）形成的水凝胶的网络松弛动力学。物理凝胶是由亮氨酸拉链端块的四聚体缔合形成的(A)。这些凝胶的最长应力松弛时间（tau(r)）随pH变化很大，从pH 8.0时的tau(r)约80 s增加到pH 7.0时的tau(r)约1000 s。利用A结构域标记形式的荧光猝灭法研究了末端块的链交换速率。荧光在荧光素标记的A溶液中猝灭；当标记的A与未标记的肽的60倍过量混合时发生脱冷。混合后的脱冷瞬态揭示了A结构域的特征链交换时间（tau(e)）。当pH值从8.0降至7.0时，tau(e)从约200秒增加到约4500秒。因此，AC(10)A水凝胶的tau(r)和A结构域的tau(e)随ph平行变化。宏观和分子性质之间的强相关性表明，网络弛豫受瞬态网络中缔合物的寿命调节。由于亮氨酸拉链链的交换速率对链间静电相互作用很敏感，人工蛋白水凝胶的弛豫行为可以通过氨基酸序列的遗传编程来系统地进行工程设计。
Network relaxation dynamics of hydrogels formed from a genetically engineered multidomain protein (AC(10)A, where A is an associative leucine zipper domain and C-10 is a random-coil polyelectrolyte domain) were investigated by shear rheometry. Physical gels form by tetrameric association of the leucine zipper end-blocks (A). The longest stress relaxation time (tau(r)) of these gels varies strongly with pH, increasing from tau(r) approximate to 80 s at pH 8.0 to tau(r) approximate to 1000 s at pH 7.0. The rate of strand exchange of the end-blocks was studied by using fluorescence quenching of the labeled form of the A domain. Fluorescence is quenched in solutions of fluorescein-labeled A; dequenching occurs when labeled A is mixed with a 60-fold excess of the unlabeled peptide. The dequenching transient after mixing reveals the characteristic strand exchange time (tau(e)) of the A domain. As pH decreases from 8.0 to 7.0, tau(e) increases from ca. 200 s to ca. 4500 s. Thus, tau(r) of AC(10)A hydrogels and tau(e) of the A domain vary in parallel with pH. The strong correlation between macroscopic and molecular properties indicates that network relaxation is regulated by the lifetime of associations in the transient network. Because the rate of leucine zipper strand exchange is sensitive to interstrand electrostatic interactions, the relaxation behavior of artificial protein hydrogels can be engineered systematically by genetic programming of the amino acid sequence.