Bühring K U, Fölsch E
Biochim Biophys Acta. 1976 Jan 14;421(1):22-32.
[3H]Dihydroaminopterin, but not [3H]methotrexate or [3H]aminopterin, was rapidly taken up by resting cell of Pediococcus cerevisiae and inhibited the uptake of (-)-5-formyl-tetrahydrofolic acid to more than 90% at a concentration of 25 muM. On the other hand 5-formyl-tetrahydrofolic acid inhibited the uptake of dihydroaminopterin to a similar extent. Dihydroaminopterin was metabolized by Pediococcus cerevisiae, but not by Lactobacillus casei, to a compound tentatively identified as dihydroaminopterin diglutamate. Methotrexate or aminopterin at a concentration of 25 muM did not inhibit the uptake of 5-formyl-tetrahydrofolic acid in Pediococcus cervisiae, but inhibited the conversion of this compound to polyglutamate forms almost completely at a level of 2.5 mu M.
[3H]二氢氨基蝶呤能被酿酒片球菌的静止细胞快速摄取，而[3H]甲氨蝶呤或[3H]氨基蝶呤则不能，在25μM的浓度下，[3H]二氢氨基蝶呤能将（-）-5-甲酰四氢叶酸的摄取抑制到90%以上。另一方面，5-甲酰四氢叶酸对二氢氨基蝶呤摄取的抑制程度与之相似。二氢氨基蝶呤可被酿酒片球菌代谢，但不能被干酪乳杆菌代谢，代谢产物初步鉴定为二氢氨基蝶呤二谷氨酸。25μM浓度的甲氨蝶呤或氨基蝶呤不抑制酿酒片球菌对5-甲酰四氢叶酸的摄取，但在2.5μM水平时几乎能完全抑制该化合物向多聚谷氨酸形式的转化。
