Table III.

Effect of various inhibitors or activators on 20S proteasome activities

Inhibitors	Concentrations	Activity (% of Control)
		Chymotrypsin like (LLVY-AMC)	Trypsin like (GGR-βNA)	PGPH (LLE-βNA)	Caseinolytic 125I-casein
ATP-Mg	3 mm	98	98	90	100
Poly-Lys	0.1% (w/v)	181	121	225	98
Hemin	50 μm	49	69	60	7
EDTA	2 mm	100	153	96	99
Indole-3-acetic acid	0.5 mm	90	91	96	103
E64	250 μm	97	104	96	–
Chymostatin	25 μm	45	83	86	–
Phenylmethylsulfonyl fluoride (PMSF)	5 mm	80	44	82	–
MG132	5 μm	27	10	100	–
	12.5 μm	19	0	100	–
	25 μm	13	0	100	–
	50 μm	7	0	–	37
PI1	5 μm	8	30	–	79
	10 μm	4	22	138	65
	20 μm	0	14	124	62
	50 μm	0	10	128	65
	100 μm	0	5	123	67
	200 μm	0	0	128	61
SDS	0.02% (w/v)	176	52	320	156

Except with SDS, 20S proteasome (5 μg) was pre-incubated with different inhibitors or activators for 15 min before the addition of substrates. With SDS, substrates and SDS were added simultaneously. Activities are expressed as a percentage of the control (with solvent alone). Values are the mean of three to five independent experiments. sds are below 10%. –, Not determined.