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Protein Purification from E. coli: Higher Yields of Tag-Free Protein

The HaloTag® Protein Purification System provides a rapid, reliable method for purification of proteins expressed in E. coli. The HaloTag® protein tag enhances expression and solubility of recombinant proteins, and allows efficient and specific capture of a protein of interest. The method overcomes limitations associated with affinity tags, such as poor capture of proteins expressed at low levels and protein loss during washing of the purification resin. Benefits of the HaloTag protein purification method include:

  • Higher solubility and activity compared to His-tag, GST and MBP affinity tags.
  • Higher yields of active protein
  • Improved protein recovery
  • Tag-free purified protein

Purifying Proteins with HaloTag

Rapid Protein Purification Protocol


A protein of interest (POI) is fused to a HaloTag® protein, which binds covalently to the HaloLink™ Resin. This covalent linkage allows stringent and lengthy wash conditions without leaching the POI off the resin. After washing, the POI is eluted by cleavage with ProTEV Protease. The ProTEV Protease contains a HQ-tag similar to His-tag, allowing protease removal with the included HisLink™ resin.

Express and Purify "Difficult" Proteins

Expression of 23 highly insoluble proteins shows that HaloTag gives better solubility than conventional His, GST, or MBP affinity tags.

Generate more soluble protein with HaloTag

Data from a set of 23 difficult-to-express proteins shows that the HaloTag® Protein Purification System yields soluble protein more frequently that His, GST, or MBP affinity tags.

HaloTag® Purified Proteins are Highly Functional

Use of gentle purification conditions, fewer protocol steps and a single native buffer results in highly active protein.

HaloTag Purified Proteins are Highly Functional

cPKA activity was determined using Kinase-Glo® assay after purification with multiple fusion tags, including HaloTag.

HaloTag® Recovers Protein When Other Tags Fail

Covalent, nonreversible binding of HaloTag to the HaloLink™ resin maximizes purification yields when compared to other fusion tags, allowing better recovery of difficult-to-express proteins.

Improved yield with challenging proteins