C-terminal Modifications

A wide variety of C‑terminal modifications can be prepared by JPT's peptide synthesis group. Typical examples are shown in the following table. Other examples include the C-terminal attachment of thiols (Cys side chain), biotin (Lys or Cys side chain), Abz (Lys side chain) and other labels or dyes.

The default C-terminus of a peptide is either a free carboxylic acid or an amide. When a peptide is meant to imitate part of a parental protein sequence, the more “native” end relates to a C-terminal amide. In addition, this modification avoids the introduction of additional charges in the peptide molecule.

Modification Structure Applications/Comments
Acid Standard (charged C-terminus)
Amide Standard (uncharged C-terminus)
Ester For structure-activity relationships (SAR), removal of charge, prodrug
Aldehyde Reactive intermediate, e.g. for non-native chemical ligation with hydroxylamines / hydrazines, reductive amination with amines
pNA (para-Nitroanilide) Protease substrate furnishes UV active pNA (405 nm) upon cleavage by proteases
Amc (7-amino-4-methylcoumarinyl) Tools for studying proteases (activity and specificity)
Hydrazide Metal-binding structural motif found especially in aspartic protease inhibitors. Availability depending on specifications
Hydroxamic acid Zinc and iron binding structural motif, especially in protease inhibitors. Examples are: inhibitors of MMPs, HDAC etc.
Chloromethyl ketone (CMK) Motif in irreversible protease inhibitors. Availability depending on peptide sequence. Please inquire
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