N-methyl-N-(t-Boc)-PEG4-acid is a PEG linker containing a t-Boc protecting group and a terminal carboxylic acid. The t-Boc protecting group is acid lablie. The terminal carboxylic acid can react with primary amines in the presence of activators such as EDC and HATU to form stable amide bonds. The hydrophilic PEG linkers increase the water solubility of the compound in aqueous media.
