N-terminal PEGylation

PEGs bearing aldehyde groups undergo reductive amination reactions with primary amines in the presence of a reducing reagent such as sodium cyanoborohydride. Unlike other electrophilically activated groups, PEGs bearing aldehyde groups react only with amines. This reaction takes place under mild conditions (pH 5–10, 6–36 hours) and
has been shown to be useful for attaching PEG to surfaces and proteins. The stability of the attachment (a secondary amine is formed upon reduction) is important for such applications as preparation of affinity supports and immobilized enzymes.

mPEG aldehydes have also been used to form acetal linkages with hydroxyl groups of polyvinyl alcohol. Utopbio’s PEG aldehydes are very popular for N-terminal PEGylation of proteins. PEG aldehydes (such as acetaldehyde and propionaldehyde) suffer from a number of disadvantages.

Acetaldehyde PEG reagents are unstable in basic media and difficult to isolate. Propionaldehyde and acetaldehyde PEG reagents have coupling challenges to proteins due to the formation of undesirable byproducts that may necessitate additional purification to obtain a pharmaceutical-grade product.

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