A modularly built bisubstrateinhibitor, the natural product pepticinnamin E (shown on the right) was sythesized for the first time. In the case of in vitro assays it inhibits the enzyme farnesyltransferase with respect to both the peptide substrate and farnesylpyrophosphate (KI = 30 and 8 μM, respectively). The inhibitoryactivity is decisively influenced by the central tripeptide unit and the absolute
Tyrosine derivatives of the formula: ##STR1## wherein: R.sub.1 is a linear or branched-chain alkyl group having 1-6 carbon atoms, terminating by a tertiary amino group; R.sub. 2 is an unsubstituted, monosubstituted or di-substituted phenyl or benzyloxy group, the substituent being --Cl, --Br, --NO.sub.2, --OCH.sub.3, --CH.sub.3 or --CF.sub.3 ; R.sub.3 is a primary, secondary or tertiary amino group or an aryl-alkylamino group having 7-9 carbon atoms; and salts of said tyrosine derivatives with pharmaceutically acceptable acids.