TABLE 1.

Substrates used in this study and the enzymes that hydrolyze them^a

Substrate	Abbreviation	Putative enzyme
l-Arginine–7-amido-4-methylcoumarin	Arg-AMC	Arginyl aminopeptidase
l-Glycine–7-amido-4-methylcoumarin	Gly-AMC	Glycyl aminopeptidase
l-Leucine–7-amido-4-methylcoumarin	Leu-AMC	Leucyl aminopeptidase
Carboxybenzoyl-glycine-glycine-arginine–7-amido-4-methylcoumarin	Z-GGR-AMC	Gingipain and other endopeptidases
Alanine-alanine-phenylalanine–7-amido-4-methylcoumarin	AAF-AMC	Clostripain and other endopeptidases
Boc-valine-proline-arginine-AMC	Boc-VPR-AMC	Gingipain and other endopeptidases
d-Phenylalanine–AMC	d-Phe–AMC	d-Phenyalanine aminopeptidase
l-Phenylalanine–AMC	l-Phe–AMC	l-Phenylalanine aminopeptidase
Ornithine-AMC	Orn-AMC	Ornithine aminopeptidase

^aAMC, 7-amido-4-methylcoumarin, the moiety that becomes fluorescent after hydrolysis of the peptide bond. All amino acids are in the l-stereoconformation unless otherwise noted. Enzymes are described as “putative” because the substrate specificity of many environmental peptidases is fairly broad, so multiple peptidases may hydrolyze any given substrate.