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新喋呤(Neopterin)是一种由鸟苷三磷酸(GTP)衍生的低分子化合物。GTP 经其环水解酶作用生成二氢新喋呤三磷酸,再经丙酮酰二氢喋呤综合酶和鸟喋呤还原酶作用生成四氢生物喋呤(BH_4),二氢新喋呤三磷酸是BH_4生物合成途径关键的中间产物,BH_4是苯丙氨酸、酪氨酸和色氨酸羟化酶的辅酶。当综合途径受阻时,此中间产物可不用酶的催化直接转变为新喋呤。如BH_4缺乏可发生血苯丙氨酸过高,因缺乏神经介质使精神严重迟钝。在临床上称为非典型苯丙酮尿,其血和尿中新喋呤浓度增高。
Neopterin is a low-molecular compound derived from guanosine triphosphate (GTP). GTP generated by its cyclohydrolase dihydrogen neopterin triphosphate, and then pyruvate dihydrogenopterin synthesis and the role of bird neopterin reductase to generate tetrahydrobiopterin (BH_4), dihydroglucate triphosphate Is a key intermediate in the BH_4 biosynthesis pathway and BH_4 is a coenzyme for phenylalanine, tyrosine and tryptophan hydroxylase. When the synthetic pathway is blocked, this intermediate can be converted directly to neopterin without the enzymatic catalysis. Such as BH_4 lack of blood phenylalanine can occur too high, due to lack of nervous mediators make mental retardation. Clinically known as atypical phenylketonuria, the blood and urine neonate high concentrations.