Ring-Opening Polymerization of Hemoglobin.
Ring-Opening Polymerization of Hemoglobin.
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DOI：
10.1021/acs.biomac.8b01789
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发表时间：
2019-02
影响因子：
6.2
通讯作者：
Takashi Matsuhira;Keizo Yamamoto;H. Sakai
中科院分区：
文献类型：
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作者：
Takashi Matsuhira;Keizo Yamamoto;H. Sakai
血红蛋白（Hb）是一种载氧蛋白质，具有α2β2四聚体结构，可可逆地解离成两个αβ二聚体（α2β2）。我们合成了一个由两个β亚基通过10 kDa聚乙二醇（PEG）链结合的环状hb -环单体。该单体通过Hb分子的αβ二聚体在PEG末端的亚基间相互作用诱导开环聚合生成超分子聚合物。闭环单体和开环超分子聚合物通过两个β亚基的分子内交联进行共价固定。对不同单体浓度下的固定产物进行定量分析，发现平衡常数(K)为5.68 mM-1，即繁殖速率与退繁殖速率常数之比。随着初始单体浓度的增加，平均聚合度（公式：见文）成比例增加。通过在2.33 mM处交联得到[公式：见文本]= 13.2 （Mn = ca. 1 MDa）的Hb聚合物。我们的Hb开环聚合新策略最终将实现高度定向和高效聚合的Hb，用于制造临床使用的人工氧载体。
Hemoglobin (Hb), an oxygen-carrying protein, has an α2β2 tetrameric structure that dissociates reversibly into two αβ dimers (α2β2 ⇄ 2αβ). We synthesized a cyclic Hb-ring monomer with two β subunits bound through a 10 kDa polyethylene glycol (PEG) chain. The monomer induced ring-opening polymerization to produce a supramolecular polymer via intersubunit interaction of αβ dimers of an Hb molecule at the PEG terminals. Both the ring-closed monomer and the ring-opened supramolecular polymer were then fixed covalently by intramolecular cross-linking of two β subunits. Quantification of fixed products at various monomer concentrations revealed the equilibrium constant ( K), a ratio of propagation and depropagation rate constants, as 5.68 mM-1. The average degree of polymerization ([Formula: see text]) increased proportionally, concomitantly with the initial monomer concentration. Hb polymer with [Formula: see text] = 13.2 ( Mn = ca. 1 MDa) was obtained by cross-linking at 2.33 mM. Our novel strategy of ring-opening polymerization of Hb will eventually realize a highly aligned and efficiently polymerized Hb for creating artificial oxygen carriers for a clinical use.