Synthesis of N alpha-protected aminoacyl 7-amino-4-methyl-coumarin amide by phosphorous oxychloride and preparation of specific fluorogenic substrates for papain
Alves, L.C.; Almeida, P.C.; Franzoni, L.; Juliano, L.; Juliano, M.A.
Peptide Research 9(2): 92-96
1996
ISSN/ISBN: 1040-5704 PMID: 8738984 Document Number: 464566
We report an improved procedure for the synthesis of fully protected aminoacyl 7-amino-4-methylcoumarin amide (MCA) employing the phosphorous oxychloride anhydride method. Seven Boc-X-MCA (where X = Arg(N-G Tos), Cys(S-Bzl), Thr(O-Bzl), Ser(O-Bzl), Phe, Leu and Gly) and Z-Tyr(O-Me) were synthesized using this procedure, with yields ranging from 50% to 75%. These aminoacyl-MCA derivatives were employed for the synthesis of epsilon-NH-2-caproyl-Leu-X-MCA, a fluorescent peptide series, which were assayed as papain substrates. All of them were completely hydrolyzed by papain, indicating that all of the Boc-X-MCA derivatives obtained were practically free of racemization. Since epsilon-NH-2-Caproyl-Leu-(S-Bzl)Cys-MCA is very susceptible to hydrolysis by papain, quite resistant to hydrolysis by chymotrypsin and not hydrolyzed by trypsin, it is recommended for assays of thiol-proteinases in which specificity is required.