Selective cleavage of proenkephalin-derived peptides (less than 23,300 daltons) by plasma kallikrein

The ability of human plasma kallikrein to hydrolyze several proenkephalin-derived peptides has been studied, including the synthetic peptides BAM 12P and peptides E, F, and B as well as synenkephalin-containing peptides (8.6, 18.2, and 23.3 kDa) purified from bovine adrenal medulla chromaffin granules. All the identified cleavages occurred either COOH-terminal to or between pairs of basic amino acids, with plasma kallikrein recognizing Lys-Lys, Lys-Arg, and Arg-Arg as processing signals. Moreover, plasma kallikrein was found to cleave at the COOH terminus of the basic pairs of amino acids preceding enkephalin sequences thereby releasing the biologically active form of the peptide with the free NH2-terminal Tyr needed for receptor recognition.