Strategy for highly selective ion-exchange capture using a charge-polarizing fusion partner

Area of Science:

• Biochemistry
• Protein Purification
• Chromatography

Background:

• Recombinant protein production requires efficient purification strategies.
• Cation-exchange chromatography is a common method, but challenges exist with basic tags.
• Proteolytic instability of basic peptide tags can hinder recovery.

Purpose of the Study:

• To develop a novel purification handle for efficient recombinant protein recovery.
• To overcome proteolytic instability associated with basic peptide tags.
• To demonstrate the efficacy of the Zbasic domain in cation-exchange chromatography.

Main Methods:

• Engineered a novel basic protein domain (Zbasic) with a constrained alpha-helical structure.
• Fused the Zbasic domain to target proteins: bacterial DNA polymerase, viral protease, and fungal lipase.
• Utilized cation-exchange chromatography for protein capture and purification.

Main Results:

• The Zbasic domain efficiently captured various fused target proteins.
• Effective protein capture was achieved even at pH values higher than the fusion protein's isoelectric point (pI).
• High purity of target proteins was obtained in a single purification step.

Conclusions:

• The Zbasic domain provides a highly efficient and selective method for recombinant protein capture.
• This strategy offers a viable alternative to standard affinity chromatography.
• The Zbasic domain enables purification under conditions that minimize host-cell protein binding.