pTWIN2 is an E. coli expression vector which can be used with the IMPACT™ Kit. A polylinker in the vector is designed for the in-frame fusion of a target gene between the modified Ssp DnaB and Mth RIR1 inteins. The presence of the chitin binding domain from Bacillus circulans facilitates purification. pTWIN vectors are designed for protein purification or for the isolation of proteins with an N-terminal cysteine and/or a C-terminal thioester. The double-stranded vector is 7192 base pairs in length.