An interface point-mutation variant of triosephosphate isomerase is compactly folded and monomeric at low protein concentrations.
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 Tm-values of 41 degrees C for wtTIM, whereas the Tm-value for the monomeric form of H47N is approximately 7 degrees C lower.
Borchert
T V
TV
EMBL, Heidelberg, Germany.
Zeelen
J P
JP
Schliebs
W
W
Callens
M
M
Minke
W
W
Jaenicke
R
R
Wierenga
R K
RK
D000818:Animals; D002942:Circular Dichroism; D007700:Kinetics; D046911:Macromolecular Substances; D016297:Mutagenesis, Site-Directed; D017433:Protein Structure, Secondary; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D013329:Structure-Activity Relationship; D013696:Temperature; D014305:Triose-Phosphate Isomerase / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure*; D014346:Trypanosoma brucei brucei / Q000201:enzymology; D014461:Ultracentrifugation
D046911:Macromolecular Substances; D015800:Protozoan Proteins; D014305:Triose-Phosphate Isomerase