Conjugation of multiple copies of polyethylene glycol to hemoglobin facilitated through thiolation: Influence on hemoglobin structure and function
Conjugation of multiple copies of polyethylene glycol to hemoglobin facilitated through thiolation: Influence on hemoglobin structure and function
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DOI：
10.1007/s10930-005-7837-2
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发表时间：
2005-04-01
期刊：
影响因子：
3
通讯作者：
Acharya, SA
中科院分区：
文献类型：
--
作者：
Manjula, BN;Tsai, AG;Acharya, SA
PEG化诱导的HbA的分子体积和溶液性质的变化已被认为是其血管收缩活性的潜在调节剂。然而，我们最近对携带两个PEG链/Hb的PEG化Hb的研究表明，Hb的血管收缩活性的调节与PEG化Hb的分子体积和溶液性质没有直接相关性，并且暗示了表面电荷和/或用PEG修饰Hb的表面图案的作用。HbA现已通过基于巯基化介导的马来酰亚胺化学的PEG化修饰，其不改变其表面电荷并缀合多个拷贝的PEG 5 K链。该方案已被优化以产生聚乙二醇化Hb（SP-PEG 5 K）（6）-Hb，其携带类似于六个PEG 5 K链/Hb -六聚乙二醇化Hb。聚乙二醇化增加了血红蛋白的O-2亲和力，并使该分子对离子强度、pH值和变构效应物的影响脱敏，这可能是蛋白质周围产生的水合PEG壳的结果。（SP-PEG 5 K）（6）-Hb中的总PEG质量、其分子体积、O-2亲和力和溶液性质类似于另一种PEG化Hb（SP-PEG 20 K）（2）-Hb，其携带两个PEG 20 K链/Hb。然而，（SP-PEG 5 K）（6）-Hb比（SP-PEG 20 K）（2）-Hb表现出显著降低的血管收缩介导的反应。这些结果表明，通过将多个拷贝的小PEG链与Hb缀合实现的增强的分子大小和溶液性质在降低其血管收缩活性方面比通过使用少量的大PEG链缀合相当的PEG质量实现的更有效。
PEGylation induced changes in molecular volume and solution properties of HbA have been implicated as potential modulators of its vasoconstrictive activity. However, our recent studies with PEGylated Hbs carrying two PEG chains/Hb, have demonstrated that the modulation of the vasoconstrictive activity of Hb is not a direct correlate of the molecular volume and solution properties of the PEGylated Hb and implicated a role for the surface charge and/or the pattern of surface decoration of Hb with PEG. HbA has now been modified by thiolation mediated maleimide chemistry based PEGylation that does not alter its surface charge and conjugates multiple copies of PEG5K chains. This protocol has been optimized to generate a PEGylated Hb, (SP-PEG5K)(6)-Hb, that carries similar to six PEG5K chains/Hb - HexaPEGylated Hb. PEGylation increased the O-2 affinity of Hb and desensitized the molecule for the influence of ionic strength, pH, and allosteric effectors, presumably a consequence of the hydrated PEG-shell generated around the protein. The total PEG mass in (SP-PEG5K)(6)-Hb, its molecular volume, O-2 affinity and solution properties are similar to that of another PEGylated Hb, (SP-PEG20K)(2)-Hb, that carries two PEG20K chains/Hb. However, (SP-PEG5K)(6)-Hb exhibited significantly reduced vasoconstriction mediated response than (SP-PEG20K)(2)-Hb. These results demonstrate that the enhanced molecular size and solution properties achieved through the conjugation of multiple copies of small PEG chains to Hb is more effective in decreasing its vasoconstrictive activity than that achieved through the conjugation of a comparable PEG mass using a small number of large PEG chains.