No Protein Detected: Elution Buffer Inadequacy

Symptom

Target protein is not detected in elution fraction despite successful capture on beads. Protein may remain bound to beads or antibody after elution attempt.

1. 1 Elution buffer pH is incorrect for disrupting antibody-antigen interaction (typically requires pH 2-3 or pH >10)
2. 2 Elution buffer ionic strength is insufficient to compete with antibody-antigen binding
3. 3 Wrong elution buffer type used (e.g., non-denaturing buffer when denaturing conditions required)
4. 4 Elution buffer concentration is too dilute to effectively disrupt protein complexes

1. 1 Verify elution buffer pH matches protocol requirements; use glycine-HCl pH 2.5 for acidic elution or pH 11 for basic elution
2. 2 Increase elution buffer ionic strength by adding NaCl to 500 mM or using high-salt buffer formulations
3. 3 Switch to denaturing elution with SDS-PAGE loading buffer (2% SDS, 100 mM DTT) at 95°C for 5 min if appropriate
4. 4 Prepare fresh elution buffer at proper concentration and verify pH immediately before use

Related Video (2)

Cell Signaling Technology ★ 85

Western Blotting Protocol

"Shows complete Western blot workflow including elution and detection steps, directly relevant to troubleshooting missing protein in eluate."

Bio-Rad Laboratories ★ 60

Setting Up and Running Mini-PROTEAN® TGX™ Precast Gels

"Demonstrates gel running and sample handling, useful for checking downstream detection after elution."