Stabilization of the single-chain fragment variable by an interdomain disulfide bond and its effect on antibody
Jian-Xin Zhao1, Lian Yang, Zhen-Nan Gu
1School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China; E-Mails: jxzhao@jiangnan.edu.cn (J.-X.Z.); yanglian27@yahoo.com.cn (L.Y.); haiqinchen@jiangnan.edu.cn (H.-Q.C.); fwtian@jiangnan.edu.cn (F.-W.T.).
Abstract:
The interdomain instability of single-chain fragment variable (scFv) might result in intermolecular aggregation and loss of function. In the present study, we stabilized H4-an anti-aflatoxin B(1) (AFB(1)) scFv-with an interdomain disulfide bond and studied the effect of the disulfide bond on antibody affinity. With homology modeling and molecular docking, we designed a scFv containing an interdomain disulfide bond between the residues H44 and L100. The stability of scFv (H4) increased from a GdnHCl(50) of 2.4 M to 4.2 M after addition of the H44-L100 disulfide bond. Size exclusion chromatography revealed that the scFv (H44-L100) mutant existed primarily as a monomer, and no aggregates were detected. An affinity assay indicated that scFv (H4) and the scFv (H44-L100) mutant had similar IC(50) values and affinity to AFB(1). Our results indicate that interdomain disulfide bonds could stabilize scFv without affecting affinity.
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