Table 2.

Secreted peptidases with specificity for lysine in position P1 higher than 30%

Plasmin and tryptase have structural similarities with trypsin; the structure of kallikrein-related peptidase 12 is not known.

Enzymes	Specificity for Lys at P1	Primary localization
	(%)
S01.151: trypsin 1	60	Intestinal tract
S01.143: tryptase alpha	56	Lung, stomach, spleen, heart, and skin
S01.020: kallikrein-related peptidase 12	55	Salivary glands, stomach, uterus, trachea, prostate, thymus, lung, colon, brain, breast, and thyroid
S01.233: plasmin	45	Plasma and many other extracellular fluids