id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-001862-a097byk5	Saisawang, Chonticha	Chikungunya nsP2 protease is not a papain-like cysteine protease and the catalytic dyad cysteine is interchangeable with a proximal serine	2015-11-24		.txt	text/plain	4515	226	50	The proteolytic activity of nsP2 has been characterized in other alphaviruses, such as Sindbis virus (SINV), Semliki forest virus (SFV) and Venezuelan Equine Encephalitis virus (VEEV), as a papain-like cysteine protease with a cysteine-histidine catalytic dyad in the active site 11, 12, [16] [17] [18] [19] . Although the dyad residues have been identified previously in other alphavirus nsP2 proteins; in SINV, SFV and VEEV 11, 12, [16] [17] [18] , the CHIKV nsP2 protease active site has not been experimentally characterized. In performing this study a structural comparison showed that CHIKV nsP2 protease is not papain-like, and we have found what appears to be a unique feature of CHIKV nsP2 protease, in which the cysteine dyad residue can be catalytically replaced by a vicinal serine. In our study the protease inhibitors leupeptin and E-64 showed little to no effect on wild type, Cys478Ala and Ser482Ala enzyme activities for all 3 substrates (Table 2) .	./cache/cord-001862-a097byk5.txt	./txt/cord-001862-a097byk5.txt