Shen R S
Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston 77550.
J Enzyme Inhib. 1985;1(1):61-6. doi: 10.3109/14756368509031282.
Catecholamines are potent noncompetitive inhibitors of dihydropteridine reductase in rat striatal synaptosomal preparations or purified from human liver. Their metabolites, except homovanillic acid, also inhibit the enzyme from both sources. The inhibitory potency of these compounds depends on the presence of the catechol or the 4-hydroxyphenyl structure, but may be modified by the 2-carbon side chain and its substituents. Indoleamines which have a hydroxylated aromatic nucleus (5-hydroxytryptamine and 5,6-dihydroxytryptamine) are equally inhibitory to the enzyme. These results suggest that biogenic amines themselves rather than their metabolites may serve as physiological inhibitors of dihydropteridine reductase in rat brain.
儿茶酚胺是大鼠纹状体突触体制剂中或从人肝脏中纯化得到的二氢蝶啶还原酶的强效非竞争性抑制剂。它们的代谢产物，除高香草酸外，也抑制来自这两种来源的该酶。这些化合物的抑制效力取决于儿茶酚或4-羟基苯基结构的存在，但可能会被2-碳侧链及其取代基所改变。具有羟基化芳香核的吲哚胺（5-羟色胺和5,6-二羟基色胺）对该酶同样具有抑制作用。这些结果表明，生物胺本身而非其代谢产物可能作为大鼠脑中的二氢蝶啶还原酶的生理抑制剂。
