The Role of Asn11 in Catalysis by Triosephosphate Isomerase.

ABSTRACT: Four catalytic amino acids at triosephosphate isomerase (TIM) are highly conserved: N11, K13, H95, and E167. Asparagine 11 is the last of these to be characterized in mutagenesis studies. The ND2 side chain atom of N11 is hydrogen bonded to the O-1 hydroxyl of enzyme-bound dihydroxyacetone phosphate (DHAP), and it sits in an extended chain of hydrogen-bonded side chains that includes T75' from the second subunit. The N11A variants of wild-type TIM from Trypanosoma brucei brucei (TbbTIM) and Leishmania mexicana (LmTIM) undergo dissociation from the dimer to monomer under our assay conditions. Values of K_as = 8 × 10³ and 1 × 10⁶ M^-1, respectively, were determined for the conversion of monomeric N11A TbbTIM

SUBMITTER: Hegazy R 

PROVIDER: S-EPMC10249627 | biostudies-literature | 2023 Jun

REPOSITORIES: biostudies-literature