TEV protease encoded by the tobacco etch virus is a catalytic domain of the Nuclear Inclusion a (NIa) protein. It is consists of 241 a.a. amino acids with the molecular weight of 27kDa. TEV recognizes the amino acid sequence of the general form E-X-X-Y-X-Q (or S)/X’, and cleaves between Q (or S)/X’. In this form X and X’ stand for any of the amino acid residues, except that X’ cannot be P. The optimal cleavage site is ENLYFQ/G. As having the absolute specificity and wildly using conditions like broad pH range and ionic strength, the TEV protease became more versatile than EK, thrombin and other protease used in biochemical applications, especially recombinant protein production. The optimal temperature for cleavage is 30°C; however, the enzyme can be used at temperatures as low as 4°C. Following digestion, TEV Protease can be removed from the reaction via the His tag sequence by Ni2+-chelate affinity chromatography.