| abstract |
A phenylalanylarginine derivative represented by the formula, ##STR1## wherein R 1 represents hydrogen or an amino-protecting group; R 2 and R 3 represent hydrogen or guanidino-protecting groups; R 4 represents naphthyl. The above compound is useful as an excellent substrate for various enzymes, such as trypsin, plasmin, kallikrein, urokinase, Cl-esterase and the like. Accordingly, the activity of enzymes can be measured by use of said compound as a substrate. |