The specificity of two proteinases that cleave adjacent to arginine, C1 esterase and acrosin, for peptide p-nitroanilide substrates.
Relative values of Vmax/Km for hydrolysis of 40 peptide p-nitroanilides catalyzed by human Cl-s and human acrosin are reported. For Cl-s, Ac-Lys(gamma Cbz)-Gly-Arg is the optimum sequence, but 25% of the substrates have (Vmax/Km)rel greater than 0.25 compared to this sequence. The best acrosin substrate tested has the sequence Tos-Gly-Pro-Arg, although (Vmax/Km)rel greater than 0.15 for more than half of the substrates. Proline at P2 is preferred by acrosin. Both enzymes prefer arginine at P1 greater than or equal to 3-fold over lysine and will not accept citrulline. In addition, occupancy of site S3 may yield an increase in Vmax/Km of greater than or equal to 10-fold with either enzyme, but many residues are accepted at S2, S3 and S4. Thus, an acrosin assay using Tos-Gly-Pro-Arg p-nitroanilide as a substrate is more than 20-times as sensitive as existing assays with blocked arginine derivatives.
Skoog
M T
MT
Merrell Dow Research Institute, Cincinnati, OH.
Mehdi
S
S
Wiseman
J S
JS
Bey
P
P
D000176:Acrosin / Q000378:metabolism*; D000813:Anilides / Q000378:metabolism*; D001120:Arginine / Q000378:metabolism; D001665:Binding Sites; D002956:Citrulline / Q000378:metabolism; D003166:Complement Activating Enzymes / Q000378:metabolism*; D003173:Complement C1s / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008239:Lysine / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism*; D013379:Substrate Specificity
D000813:Anilides; D010455:Peptides; D002956:Citrulline; D001120:Arginine; D003166:Complement Activating Enzymes; D012697:Serine Endopeptidases; D000176:Acrosin; D003173:Complement C1s; D008239:Lysine