Tsybovsky Y, Shubenok DV, Kravchuk ZI, Martsev SP.
(2007)
Protein Eng Des Sel.,
20,
481-490 |
Folding |
C-terminal hexahistidine tag |
Protein recombinantly expressed as and refolded from inclusion bodies. |
Escherichia coli |
BL21(DE3)pLysS |
37.0 |
3 h |
pETVL |
Purification of the VL domain
Expression of the VL domain was performed as we described earlier (Martsev et al., 2000). Inclusion bodies, which contained the major (95%) fraction of the recombinant protein, were separated from the soluble fraction of the cell lysate by centrifugation for 30 min at 35 000 g.
|
IPTG |
OD n/a =
n/a |
Sonication |
None |
Metal affinity chromatography |
insoluble |
Dialysis |
150-200 mL of 50 mM Tris-HCl, pH 8.0, containing 0.15 M NaCl and 1 mM phenylmethanesulfonyl fluoride (PMSF) |
6 M guanidine hydrochloride (Gdn–HCl) |
5, 3 and 1 M urea in 0.1 M sodium phosphate, pH 2–3, and then dialyzed against 0.1 M Tris, pH 8.1, and, finally, against 0.1 M sodium phosphate, pH 7.4 |
Metal affinity chromatography |
no |
2.0 |
25.0 |
n/a |
n/a |
None |
n/a,n/a,n/a |
The VL domain purified from inclusion bodies was refolded by stepwise dialysis procedure according to the two refolding protocols (Fig. 1). To obtain the VL-1 conformer, the refolding protocol-1 was applied in which the purified VL domain was sequentially dialyzed against 5, 3 and 1 M urea in 0.1 M sodium phosphate, pH 2–3, and then the same buffer without the denaturant. At this stage, some variations in the refolding buffer composition, pH and ionic strength (Fig. 1, upper line) did not change the final conformation. The protein was then dialyzed against 0.1 M Tris, pH 8.1, and, finally, against 0.1 M sodium phosphate, pH 7.4. |
Unspecified |
None |
None |
n/a |
n/a |
n/a |
In this paper, we provide the first description of the two stable and functional conformations of an antibody domain.The key difference between the protocols is exposure to low pH (pH 2–3) in refolding protocol-1, which was critical to obtain the conformation denoted as VL-1 |