The starch-binding domain as a tool for recombinant protein purification

Area of Science:

• Biotechnology
• Protein Biochemistry
• Affinity Chromatography

Background:

• Recombinant protein purification commonly utilizes affinity tags like the histidine tag (Histag).
• Developing alternative affinity tags is crucial for improving purification efficiency and cost-effectiveness.

Purpose of the Study:

• To evaluate the efficacy of a tandem starch-binding domain tag (SBDtag) for recombinant protein purification.
• To compare the performance of the SBDtag against the traditional Histag.
• To demonstrate the use of inexpensive raw starch as a purification matrix.

Main Methods:

• Four different proteins were genetically fused to the SBDtag.
• Fusion proteins were purified using affinity chromatography with either Histag or SBDtag.
• Purification efficiency was assessed by comparing yields and purity.
• The ability of SBDtag fusions to bind to raw starch from various sources (corn, rice, potato, barley) was tested.

Main Results:

• The SBDtag demonstrated superior performance in protein purification compared to the Histag.
• Fusion proteins exhibited efficient adsorption to raw corn starch.
• Two SBDtag fusion proteins were successfully purified directly from crude bacterial extracts using raw starch from multiple plant sources.

Conclusions:

• The SBDtag is a highly effective affinity tag for recombinant protein purification.
• Raw starch serves as a cost-effective and efficient matrix for SBDtag-based purification.
• This method presents a viable alternative for large-scale and economical protein purification.