Improved non-chromatographic purification of a recombinant protein by cationic elastin-like polypeptides

Biomacromolecules. 2007 May;8(5):1417-24. doi: 10.1021/bm060849t. Epub 2007 Apr 4.


This paper reports an improvement in the purification of thioredoxin (Trx) expressed from E. coli by inverse transition cycling (ITC) using cationic elastin-like polypeptides (ELPs). Two ELP libraries having 2% and 5% lysine residues and molecular weights ranging from 4 to 61.1 kDa showed greater salt sensitivity in their inverse transition behavior than purely aliphatic ELPs. Expression yield of Trx-ELP fusions was an unpredictable function of guest residue composition, but reducing the molecular weight of the ELP tag generally increased Trx yield. A cationic 4.3 kDa ELP is the shortest ELP used to purify any protein by ITC to date. A 15.9 kDa ELP with a guest residue composition of K:V:F of 1:7:1 was found to be the optimal cationic tag to purify Trx, as it provided 50% greater Trx yield and only required one-fifth the added NaCl for purification of Trx as compared to previously used aliphatic ELP tags.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Cations / chemistry
  • Elastin / biosynthesis
  • Elastin / chemistry*
  • Elastin / genetics
  • Escherichia coli / chemistry
  • Escherichia coli / genetics
  • Molecular Sequence Data
  • Peptide Library
  • Peptides / chemistry*
  • Peptides / genetics
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / isolation & purification*
  • Sodium Chloride / chemistry
  • Thioredoxins / biosynthesis
  • Thioredoxins / chemistry
  • Thioredoxins / isolation & purification*


  • Cations
  • Peptide Library
  • Peptides
  • Recombinant Fusion Proteins
  • Sodium Chloride
  • Thioredoxins
  • Elastin