An interface point‐mutation variant of triosephosphate isomerase is compactly folded and monomeric at low protein concentrations

Open Access
Publisher Website
Google Scholar
Abstract
Wild‐type trypanosomal triosephosphate isomerase (wtTIM) is a very tight dimer. The interface residue His‐47 of wtTIM has been mutated into an asparagine. Ultracentrifugation data show that this variant (H47N) only dimerises at protein concentrations above 3 mg/ml. H47N has been characterised at a protein concentration where it is predominantly a monomer. Circular dichroism measurements in the near‐UV and far‐UV show that this monomer is a compactly folded protein with secondary structure similar as in wtTIM. The thermal stability of the monomeric H47N is decreased compared to wtTIM: temperature gradient gel electrophoresis (TGGE) measurements give T m‐values of 41°C for wtTIM, whereas the T m‐value for the monomeric form of H47N is approximately 7°C lower.