Table 2.

Comparison of the specific activities of various DUBs against Cbz-LRGG-AMC to those against ¹²⁵I-labeled Ub-PESTc.

	Specific activity against
DUBs	Cbz-LRGG-AMC	125I-labeled Ub-PESTc
YUH1	3.2 x 10-10	5.1 x 10-8
yUBP6	2.0 x 10-12	3.2 x 10-9
cUCH-1	0.7 x 10-11	2.8 x 10-7
cUCH-6	1.2 x 10-10	1.1 x 10-6
cUCH-8	0.9 x 10-11	3.3 x 10-7
cUBP41	2.5 x 10-11	5.3 x 10-7

The amounts of the enzymes used were 0.1 μg and 5 μg for assaying the hydrolysis of ¹²⁵I-Ub-PESTc and Cbz-LRGG-AMC, respectively. Incubations were performed at 37 °C for various periods to obtain initial velocity for each DUB. The specific activities of the enzymes were expressed as mol ¹²⁵I-PESTc released into acid-soluble products or AMC released into the solution per min per mg protein.