EN
The Stoffel DNA fragment, shortened by 12 bp from 5' end, coding for StoffelDNA polymerase (missing 4 amino acids at N-terminus of Stoffel amino-acids sequence) from the thermophilic Thermus aquaticus (strain YT-1) was amplified, cloned and expressed in Escherichia coli. The recombinant Stoffel fragment contained a polyhistidine tag at the N-terminus (21 additional amino acids) that allowed its single-step isolation by Ni2+ affinity chromatography. The enzyme was characterized and displayed high DNA polymerase activity and thermostability evidently higher than the native Tag DNA polymerase.