Synthesis of sweet DOPA peptide and its analogues.

Asp-DOPA-OMe, Asp-DOPA-OnBu, and Asp-dopamine were prepared according to the new general procedure described for DOPA dipeptides.

Coordination of copper(II) ions to catechoyl-dipeptides, the inhibitors of leucine aminopeptidase and ribonucleotide reductase.

Potentiometric and spectroscopic study of the coordination ability of 2,3- and 3,4-dihydroxybenzoyl-dipeptides has shown that catechoyl-dipeptides are very strongly-binding ligands. The coordination begins at the catechol site at pH below 4. In the case of 2,3-dihydroxy derivatives the peptide unit may also be involved in the copper(II) ion coordination via its peptide nitrogens. The biological tests have indicated that the studies ligands may be effective inhibitors of ribonucleotide reductase in some cases, with a reasonable level of selectivity.