Table 2.

IC₅₀ comparison of disulfiram inhibition of PL^pros in the absence or presence of other inhibitors by proteolytic activity assay.

Enzyme	IC50 (μM)	IC50 fold decrement
SARS-CoV PLpro inhibited by
disulfiram	14.2 ± 0.5	–
with 6TG (15 μM)	21.8 ± 1.0	0.7
with NEM (4 μM)	18.1 ± 0.7	0.8
with βME (5 mM)	>300
SARS-CoV PLpro C271A inhibited by disulfiram	62.7 ± 2.0	–
MERS-CoV PLpro inhibited by
disulfiram	22.7 ± 0.5a,b,c	–
with 6TG (15 μM)	14.5 ± 0.4a	1.6
with MPA (150 μM)	21.7 ± 0.4	1.0
with 6TG (10 μM) and MPA (100 μM)	13.7 ± 1.0b	1.7
with 6TG (15 μM) and MPA (150 μM)	4.4 ± 0.2c	5.2
with βME (5 mM)	>300

^a–cp < 0.05 by Student's T test.