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