Glyoxalase metabolism

The pathway map below for Neospora caninum is same as the glyoxalase metabolism pathway for Toxoplasma gondii. The orthologs of all the enzymes of this pathway in T. gondii and Plasmodium falciparum are also present in N. caninum. In Apicomplexa, D-lactate is produced in addition to L-lactate (glycolysis). The stereo-specificity of lactate dehydrogenase suggests the possibility of D-lactate being produced from methylglyoxal. In glycolysis, one of the intermediates is glycerone phosphate (dihydroxyacetone phosphate). The conversion of it to methylglyoxal, a toxic product can take place either spontaneously or by the action of enzyme methylglyoxal synthase in various organisms. In P. falciparum, there are no genes for methylglyoxal synthase identified and no enzymatic activity was experimentally detected. This suggests that this reaction takes place spontaneously. The genes for glyoxalase-I and glyoxalase-II are present in P. falciparum genome and their activities are also experimentally detected with parasite having 2-3 fold higher specific activities. The presence of different kinetic properties between enzymes from parasite material and from that of erythrocytes was also observed [1]. The genes for glyoxalase I and II were identified in N. caninum and T. gondii genomes. It suggests the presence of this pathway and production of D-lactate from methylglyoxal in N. caninum.

Open in a new window

Sources and fates of metabolites