The Effect of a Peptide Substrate Containing an Unnatural Branched Amino Acid on Chymotrypsin Activity

7-Amino-4-methylcoumarin (AMC) is a low molecular weight fluorescent probe that can be attached to peptide enable the detection of specific proteases, such as chymotrypsin, expressed in certain diseases. Because this depends on specificity protease toward peptidyl AMC, development substrates required. To investigate AMC compounds incorporating four different amino acid residues were prepared by liquid-phase synthesis. Two unnatural acids, 2-amino-4-ethylhexanoic (AEH) and cyclohexylalanine (Cha), used substrate these acids have structures from natural acids. AEH was synthesized using diethyl acetamidemalonate starting material. The containing Cha had high hydrophobicity showed reaction velocity with chymotrypsin. Although branched side chain hydrophobicity, it velocity. aromatic phenylalanine less hydrophobic than substrates, but chymotrypsin highest for compound. These results demonstrated not only affected aromaticity, also structural expanse substrate.