title: Characterization of the folic acid C9-N10-cleaving enzyme of Dictyostelium minutum V3.
abstract: Folic acid is a chemoattractant for the slime mold Dictyostelium minutum V3. The activity of extracellular folic acid is regulated by a folic acid C9-N10 splitting enzyme (FAS). The products were identified as pterin-6-aldehyde and p-amino-benzoylglutamic acid. The enzyme was stabilized by EDTA. For the extracellular enzyme, the Km was 10(-7) M, and the optimal pH was 4.0. During starvation, FAS activity was mainly secreted into the medium; after 3 h, a plateau was reached. The membrane-bound activity was constant, but only 12% of the extracellular activity at 3 h. Intracellular activity also increased up to 3 h to a level of 23% of the extracellular FAS. The substrate recognition of FAS was found to be based on 4-O or N3 or both, N5 or N8 or both, N10, and the p-aminobenzoic acid moiety, whereas 2-NH2, N1, and the glutamic acid moiety were not recognized. Other slime mold species were found to secrete FAS with 20-fold or more reduced activity than D. minutum V3.
mesh_terms: D000619:Aminohydrolases / Q000378:metabolism*; D004023:Dictyostelium / Q000201:enzymology*; D005492:Folic Acid / Q000378:metabolism*; D005971:Glutamates / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D015800:Protozoan Proteins; D011621:Pteridines / Q000378:metabolism; D011622:Pterins; D013045:Species Specificity
chemical_list: D005971:Glutamates; D015800:Protozoan Proteins; D011621:Pteridines; D011622:Pterins; C005926:2-amino-4-hydroxy-6-formylpteridine; D005492:Folic Acid; C011398:4-aminobenzoylglutamic acid; D000619:Aminohydrolases; C020144:folic acid deaminase, Dictyostelium discoideum