Custom synthesis for His-tag (polyhistidine) PEGylation reagent is available for PEG-NTA. It includes mPEG-NTA, NTA-PEG-NTA, 4/8-Arm PEG-NTA at various MW. Nitrilotriacetic acid (NTA)-PEG conjugate in the form of a metal complex with Co colbat, Ni Nickel form a chelating complex with polyhistidine tag. A polyhistidine-tag consists of at least six histidine (His) residues, often at the N- or C-terminus of the protein. His-tag synonyms: hexa histidine-tag, 6xHis-tag, His6 tag. His-tag is a registered Trademark of EMD Biosciences. His-tag is common to tag recombinant proteins for easy purification. mPEG-NTA can effectively PEGylate polyhistidine tagged proteins. Contact us.