Patent ID: 7846719

Claim:
A vector comprising a nucleotide sequence encoding a fusion protein, wherein the fusion protein comprises, from the amino-terminus to the carboxyl-terminus, in the order, a thioredoxin (Trx) tag, a (His) 6 -tag, a thrombin cleavage site (TCS), an S-tag, an enterokinase cleavage site (ECS), a linker and a glutaminyl cyclase (QC), wherein the linker is immediately adjacent to the amino-terminus of the QC, and the linker consists of a Factor Xa cleavage site (FCS) and at least one (His) x -tag, wherein x is an integer of at least 6, and the (His) x -tag is immediately adjacent to the amino-terminus of the FCS, wherein a soluble QC is expressed in an Escherichia coli ( E. coli ) cell transformed with the vector.