De Wit R J, van der Velden R J, Konijn T M
J Bacteriol. 1983 May;154(2):859-63. doi: 10.1128/jb.154.2.859-863.1983.
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.
叶酸是微小盘基网柄菌V3的一种化学引诱剂。细胞外叶酸的活性受叶酸C9-N10裂解酶（FAS）调控。其产物被鉴定为蝶呤-6-醛和对氨基苯甲酰谷氨酸。该酶可被EDTA稳定。对于细胞外酶，Km为10^(-7) M，最适pH为4.0。在饥饿期间，FAS活性主要分泌到培养基中；3小时后达到平稳状态。膜结合活性保持恒定，但在3小时时仅为细胞外活性的12%。细胞内活性在3小时内也增加到细胞外FAS活性的23%。发现FAS的底物识别基于4-O或N3或两者、N5或N8或两者、N10以及对氨基苯甲酸部分，而2-NH2、N1和谷氨酸部分不被识别。发现其他盘基网柄菌物种分泌的FAS活性比微小盘基网柄菌V3降低20倍或更多。
