Starch Binding Domain Fusion for Protein Purification
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Solution Overview
Problem
Current protein purification methods using affinity chromatography are laborious, expensive, and inefficient, especially in conditions with EDTA-containing samples, and the existing protein tags are large compared to the target protein, limiting their effectiveness.
Innovation Solution
A starch binding domain (SBD) with a dissociation constant (Kd) of 0.5–2.29 μM is used to create a recombinant protein purification system, where the SBD is fused with a polypeptide of interest, allowing direct application to an affinity matrix, elution with a suitable buffer, and dialysis, utilizing starch as an affinity matrix for efficient protein purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional affinity chromatography methods are used for protein purification, then proteins can be isolated, but the process becomes laborious and expensive
Solution Approach 1:
The invention extracts only the essential starch-binding functional domain from the complete glucoamylase enzyme, creating a minimal SBD tag that retains affinity for starch while eliminating unnecessary catalytic and other functional domains. This extracted SBD tag can be fused to target proteins to enable simple starch-based affinity purification, resolving the contradiction between purification effectiveness and operational convenience.
Solution Approach 2:
The invention uses inexpensive, readily available starch (such as corn starch) as the affinity ligand instead of expensive purified proteins or complex synthetic ligands. The starch can be used in its natural polymeric form without requiring purification or special preparation, making the purification process cost-effective and accessible while maintaining reliable protein isolation.
2Reliability
If large fusion protein tags are used for purification, then affinity chromatography can be achieved, but the tag size becomes larger compared to the target protein
Solution Approach 1:
The invention extracts only the essential starch-binding functional domain from the complete glucoamylase enzyme, creating a minimal SBD tag that retains affinity for starch while eliminating unnecessary catalytic and other functional domains. This extracted SBD tag can be fused to target proteins to enable simple starch-based affinity purification, resolving the contradiction between purification effectiveness and operational convenience.
3Reliability
If conventional protein tags are used, then purification can be performed, but the system fails in EDTA-containing samples
Solution Approach 1:
The invention uses inexpensive, readily available starch (such as corn starch) as the affinity ligand instead of expensive purified proteins or complex synthetic ligands. The starch can be used in its natural polymeric form without requiring purification or special preparation, making the purification process cost-effective and accessible while maintaining reliable protein isolation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables high-yield, high-purity protein purification with a wide range of optimal pH, suitable for large-scale applications, and is effective in EDTA-containing samples, with the SBD being a smaller tag than traditional fusion protein tags, improving protein production, activity, and stability.
Implementation Method 1
the SBD being fused to a polypeptide of interest, allowing direct application to an affinity matrix
Implementation Method 2
eluting the affinity matrix by eluent; and (c) dialyzing the eluent
Data Source
AI summary
A recombinant protein is prepared comprising a polypeptide of interest and a starch binding domain (SBD). The said SBD is obtainable from glucoamylase of fungi genus Rhizopus. The said recombinant protein comprising the said SBD can be purified by contacting with an affinity matrix such as starch, the SBD binds to the affinity matrix to isolate the recombinant protein. The recombinant protein can be purified by separating the association between the SBD and the affinity matrix by acid, alkaline, salt, or sugar. The polypeptide of interest may be an antibody, an antigen, a therapeutic compound, an enzyme, or a protein and may apply in pathogen destruction, vaccine producing, and oral care product manufacturing. The SBD further provides as a tool to screen or identify polysacchrides.