Two-in-one protein tag enables the soluble expression and calcium-dependent purification of single-chain antibody fragments.

ABSTRACT: Single-chain variable fragments (scFvs) antibodies are used in diagnostic and therapeutic biopharmaceuticals. However, its production is limited due to insoluble expression and lack of a universal purification ligand. Here, we report a novel two-in-one protein tag, termed CSQ-tag, utilizing a calsequestrin (CSQ) protein to enable the soluble expression and calcium-dependent purification for scFvs. The CSQ-tag enhanced the solubility of four different therapeutic scFvs with an average solubility of 83.8 ± 4.6% in the BL21(DE3) strain, despite its reducing cytoplasmic environment. Compared to other tags, CSQ-tag showed superior solubility, with 1.8-fold higher solubility than MBP-tag across four scFvs. The solubility enhancement of the CSQ-tag is attributed to two main characteristics: highl

SUBMITTER: Lee J 

PROVIDER: S-EPMC12946349 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature