PEG和DBBF修饰猪血红蛋白及其携氧性质

采用聚乙二醇 (PEG)修饰蛋白质可以增大蛋白质的分子量 ,改善其生物相容性和在生物体内的停留时间。而小分子交联修饰则可以稳定血红蛋白的高级结构 ,改善其对组织的递氧能力。比较了 4种方法活化的PEG衍生物对猪血红蛋白的修饰效率、修饰产物的携氧功能和稳定性等。PEG的分子量、轭合PEG的数量及变构效应物的存在与否都会影响修饰产物的性质 ;考察了双 3,5二溴水杨酸延胡索酸酯 (DBBF)修饰猪血红蛋白的反应条件以及修饰产物的物理特性和携氧能力 ,并进一步采用PEG和DBBF联合修饰猪血红蛋白。结果证明 ,联合修饰产物具有稳定的四聚体结构 ,分子量达 10 70 0 0 ,半饱和氧分压P50 在 3.33kPa左右 ,接近于生理条件下人体红细胞的P50 值。

PEG and DBBF Modified Porcine Hemoglobin and Their Oxygen-carrying Capacity

Modifications of proteins with polyethylene glycol (PEG) have been proven to enlarge molecule size of proteins, to prolong their retention time in the circulation as well as blunt immune or allergic reactions. Hemoglobin cross linked with small molecular modifiers turns out to be more stable and to have better oxygen carrying capacity. In the present study, four derivatives of PEG with different activation groups, and several PEGs with different molecular weights were covalently bound to porcine hemoglobin (pHb). PEG pHbs exhibi ted a variety of differences in their properties depending on the molecular weights of the used PEGs, the amounts of bound PEGs and the presence or absence of allosteric cofactors. The optimal modification conditions for bis (3, 5 dibromosalicyl) fumarate (DBBF) as well as the physical features and oxygen carrying capacity of DBBF modified pHb were evaluated. Furthermore, both PEG and DBBF were used simultaneously to modify pHb. The results indicate that the pHbs modified with PEG and DBBF have more stable tetrameric conformations with a molecular weight of 107 kD. Their oxygen half saturation pressure ( P 50 ) is around 3.33 kPa which approximates the physiological P 50 of human red blood cells.