SPDP-PEG8-tBu ester is an SPDP derivative bearing a PEG spacer with t-butyl ester end group. The pyridyldithiol reactive groups can react cysteine sulfhydryls with to form cleavable (reducible) disulfide bonds, which makes it an ideal conjugate tool for cysteine residues.
AxisPharm offers 3000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.