Peptide and protein fusions to thioredoxin, thioredoxin-like molecules, and modified thioredoxin-like molecules

A DNA comprising a sequence which encodes thioredoxin-G-S-G-G-D-D-D-D-K-N-des-Pro-II-11 (SEQ ID NO:

• 14) and encodes a histidine patch.

An isolated DNA encoding a fusion protein comprising a first DNA sequence encoding a first protein and a second DNA fused in frame and encoding a second protein, wherein said first DNA is SEQ ID NO:

• 25.

A plasmid DNA molecule comprising a first DNA sequence encoding thioredoxin fused in frame to a second DNA sequence encoding a second protein,

• said first and second sequences together comprising a fusion sequence encoding a fusion protein,
• wherein said first DNA further comprises a sequence encoding at least two metal chelating histidine residues separated by 10 or more amino acids and responsible for chelation of said fusion protein to a metal,
• said fusion sequence under the control of an expression control sequence comprising a promoter functional in E. coli, a ribosome binding site, an origin of replication and an optional selectable marker, said control sequence capable of directing the expression of said fusion protein in a selected host cell.

A fusion protein comprising a thioredoxin protein fused in frame to a second protein, said fusion protein further comprising at least two metal chelating histidine residues separated by 10 or more amino acids and responsible for chelation of said fusion protein to a metal.

A method for purifying a protein comprising the steps of:

• (a) modifying said protein to comprise at least two histidine residues, separated by a sequence of 10 or more amino acids and responsible for chelation of said protein to a metal affinity matrix,
• (b) exposing said modified protein to said metal affinity matrix to form a protein metal complex, and
• (c) recovering said protein.

A method for purifying a fusion protein comprising the steps of:

• (a) modifying said fusion protein to comprise at least two histidine residues, separated by a sequence of 10 or more amino acids and responsible for chelation of said fusion protein to a metal affinity matrix,
• (b) exposing said modified fusion protein to said metal affinity matrix to form a fusion protein metal complex, and
• (c) recovering said protein.

A method for purifying a protein having at least two histidine residues, separated by a sequence of 10 or more amino acids and responsible for chelation of said protein to a metal affinity matrix, comprising the steps of:

• (a) exposing said modified protein to said metal affinity matrix to form a protein metal complex, and
• (b) recovering said protein.