Design, creation, and characterization of a stable, monomeric triosephosphate isomerase.

Protein engineering on trypanosomal triosephosphate isomerase (TIM) converted this oligomeric enzyme into a stable, monomeric protein that is enzymatically active. Wild-type TIM consists of two identical subunits that form a very tight dimer involving interactions of 32 residues of each subunit. By replacing 15 residues of the major interface loop by another 8-residue fragment, a variant was constructed that is a stable and monomeric protein with TIM activity. The length, sequence, and conformation of the designed fragment were suggested by extensive modeling.