Table I.

Purification of 20S proteasome from maize roots

Step	Protein	Total Activity	Specific Activity	Yield	Purification Factor
	mg	nmol h−1	nmol mg−1 h−1	%
Crude extract	2,175	16,706	7.7	100	1
DEAE-Sepharose	681	16,154	24	97	3
S-300 HR	162	4,128	25	25	3.2
MONO-Q	12.6	1,073	85	6.4	11
Phenyl-superose	2.1	430	205	2.6	27

The activity was determined through the chymotrypsin-like activity of the 20S proteasome, with N-succinyl-L-L-V-Y-7-amido-4-methylcoumarin (Suc-L-L-V-Y-AMC) as substrate (final concentration 100 μm), as described in “Materials and Methods.”