Table 4.

PSA substrate hydrolysis by purified intracellular proteases^a

		pmol of substrate hydrolyzed/min/200 pmol of protease Cathepsins
Peptide sequenceb	PSA	B	C	D	Esterasec
EHSSKLQ	31.6	4.3	UD	2.2	UD
HSSKLQ	62.7	17.3	UD	3.8	UD
SKLQ	29.6	31.2	UD	6.4	UD
KLQ	0.4	87.0	UD	ND	UD
LQ	UD	190	UD	20.0	UD
Q	UD	1.0	UD	1.1	0.9

^aUD, undetectable (<0.1 pmol substrate of hydrolysis/min/200 pmol of protease); ND. Not done.

^bSubstrates at 0.2 mm concentration in PSA assay buffer except SKLQ, KLQ, and LQ, in 1.4% acetonitrile/buffer, and Q-AMC. in 0.2% formic acid/buffer (pH 7.8).

^cEsterase from porcine liver.