| abstract |
A peptide having the following sequence is added to a useful protein as a peptide tag to express it. X m (PY n ) q PZ r Wherein X, Y and Z are independently selected from R, G, S, K, T, L, N, Q and H, wherein at least one of Y is K, L, N, Q, H Or R. < / RTI > m is an integer of 0 to 5, n is 1, 2 or 3, q is an integer of 1 to 10, and r is an integer of 0 to 10. |