Unusual benefits of macromolecular shielding by polyethylene glycol for reactions at the diffusional limit: the case of factor VIIai and tissue factor.
Unusual benefits of macromolecular shielding by polyethylene glycol for reactions at the diffusional limit: the case of factor VIIai and tissue factor.
复制标题
聚乙二醇对扩散极限反应的大分子屏蔽的不寻常益处：以因子 VIIai 和组织因子为例。
DOI：
10.1021/bi0204544
复制
发表时间：
2002
期刊：
影响因子：
2.9
通讯作者：
Nelsestuen,GaryL
中科院分区：
文献类型：
--
作者：
Stone,Matthew;Harvey,StephenB;Kisiel,Walter;Foster,Donald;Nelsestuen,GaryL
用聚乙二醇（PEG）修饰蛋白质可以延长动物的循环寿命，降低蛋白质的抗原性。这些好处可能来自PEG的作用机制，蛋白质表面的分子屏蔽，以及与其他大分子的相互作用降低。依赖于大分子结合功能的蛋白质似乎不是PEG修饰的好目标，因为功能丧失可能会减轻其益处。事实上，研究了peg修饰因子VIIa和活性位点阻断的凝血因子Xa或IXa的高功能损失。一个令人惊讶的发现是，peg修饰的活性位点阻断因子VIIa （peg - viai, peg - 40000）保留了40%的功能，尽管循环寿命增加了18倍。功能损失和循环寿命增加之间的差异与受组装扩散步骤而不是化学结合步骤限制的过程一致。peg - 40000对viai扩散的影响相对于其在化学结合过程中对分子屏蔽的潜在影响来说是很小的（约为3倍）。这些特性扩展到VIIai突变体（P10Q/K32E, QE-VIIai），其功能比野生型VIIai高25倍。总的来说，peg修饰蛋白的性质可以提示动力学机制的特征，并可能为抗凝治疗提供增强蛋白。
Protein modification with poly(ethylene glycol) (PEG) can prolong circulatory lifetime and lower protein antigenicity in an animal. These benefits may arise from the proposed mechanism of PEG action, molecular shielding of the protein surface, and lowered interaction with other macromolecules. Proteins that depend on macromolecule association for their function would not seem good targets for PEG modification as the benefits may be mitigated by loss of function. Indeed, high loss of function applied to PEG-modified factor VIIa and to active site-blocked blood clotting factors Xa or IXa was studied. A surprising finding was that PEG-modified, active site-blocked factor VIIa (PEG-VIIai, PEG-40 000) retained 40% of its function despite an 18-fold increase in circulatory lifetime. The discrepancy between functional loss and increased circulatory lifetime was consistent with a process that was limited by the diffusion step of assembly rather than the chemical binding step. The impact of PEG-40 000 on diffusion of VIIai is small (about 3-fold) relative to its potential impact on molecular shielding during the chemical binding step of association. These properties extended to a mutant of VIIai (P10Q/K32E, QE-VIIai) that has 25-fold higher function than wild-type factor VIIai. Overall, properties of PEG-modified proteins can suggest features of the kinetic mechanism and may provide enhanced proteins for anticoagulation therapy.