Maleimide PEG NHS, MAL-PEG-NHS

Micro- and Mid-Scale Maleimide-Based Conjugation of Cytotoxic Drugs to Antibody Hinge Region Thiols for Tumor Targeting

and stability. Here we elaborate detailed protocols using maleimide-based chemistry for the conjugation to reduce hinge disulfides in antibodies by several cytotoxic drugs. We present a method for the initial characterization of the reduction/alkylation reaction

聚乙二醇修饰反应类型

修饰，常有几个氨基被修饰，导致多态混合物的产生，即使只结合一个聚乙二醇，也可能结合在不同的氨基位点上，产生位点异构体。由于蛋白质只有一个末端氨基，因此对它的修饰可以减少多态混合物和位点异构体的产生，但修饰末端氨基的聚乙二醇反应时需使用硼氢氰化钠，有一定的毒性。氨基修饰最常用的修饰剂为SS-PEG、SC-PEG、SPA-PEG、NHS-PEG2和ALD-PEG等。 巯基修饰 活化半胱氨酸的巯基往往处于蛋白质的活性中心部位，位于蛋白质表面的自由巯基远少于氨基，因此修饰效率低下，修饰后蛋白活性损失较大

PEGylation of Antibody Fragments for Half-Life Extension

of polyethylene glycol (PEG) chain to protein using PEGylation technology. The most suitable approach employs PEG-maleimide attachment to cysteines, either to the free hinge cysteine or to C-terminal cysteines involved in interchain disulfide linkage of the heavy