The Salt Secret 90% of Purification Teams Overlook

Most protein purification teams treat salt concentration in loading buffers as an afterthought—just a standard 150 mM NaCl to mimic physiological conditions, right? It seems safe, familiar, and unlikely to cause trouble.

The reality flips that entirely: high-salt loading (0.5–2 M NaCl) can often strip away 80–90% of non-specific contaminants before your target even binds, delivering dramatically cleaner protein in fewer steps—if your affinity system can handle it.

Traditional tags struggle here. His-tags tolerate ~1 M but lose capacity and grab junk above that. GST and Strep-tags max out at 0.2–0.5 M before binding weakens. Chitin works to ~1 M but rarely eliminates nucleic acid carryover.

TriAltus' CLīM™ (CL7/Im7) platform changes the game. Its femtomolar affinity holds firm through up to 3 M salt —letting us aggressively wash away DNA/RNA complexes, sticky contaminants, and weakly associated proteins that plague nucleic acid-binding enzymes, membrane proteins, and anything with exposed hydrophobics.

Why High Salt Works (And When It Fails)

The mechanism: High salt disrupts electrostatic interactions—the main driver of non-specific binding between your target, column matrix, and contaminants. Weakly charged impurities wash away while your high-affinity tag keeps the real protein locked down.

Best targets:

• DNA/RNA-binding proteins (TFs, polymerases, CRISPR nucleases): Salt releases bound nucleic acids that co-purify otherwise

• Soluble, well-folded proteins: Usually tolerate 0.5–1 M easily

• Membrane proteins (post-solubilization): Helps separate peripheral from integral components

Watch out for:

• Highly hydrophobic proteins: May aggregate >1 M (test gradients)

• Poorly folded targets: Salt exacerbates misfolding

Pro tip: Start at 0.5 M NaCl. If purity plateaus, step to 1 M. Monitor with SDS-PAGE or A280/A260 ratios to catch nucleic acid carryover.

The Resin Comparison That Matters

You Don't Need to Redesign—Just Receive Better Material

High-salt purification sounds simple but demands an affinity system that won't flinch. Most suppliers stick to low-salt protocols because their platforms can't handle more.

TriAltus built CLīM™ for exactly this: ultra-pure, high-activity enzymes delivered to your door, already run through conditions your in-house workflow would struggle to replicate.

If you're battling persistent co-purifying nucleic acids, inconsistent activity, or purity plateaus around 80–90%, high-salt CLīM™ purification might be the missing variable.

Ready to test it on your toughest target? Message us to discuss your protein and see how high-salt, one-step purification can simplify your results.