Table 2. IN solubility was tested in different solvents.

IN solubility (mg ml−1)	1 M NaCl 7 mM CHAPS	1 M NaCl	0.5 M NaCl
E. coli	4.0–5.0	0.1–0.5	0.1–0.3
Insect	4.0–5.0	0.1–0.5	0.1–0.3
Mammalian	4.0–5.0	2.0–3.0	2.0–3.0

IN, integrase.

The proteins produced in mammalian cells showed increased solubility compared to the E. coli and insect cell production.