Effect of Phenylalanine-ammonia-lyase on Phenylketonuria

苯丙氨酸解氨酶（PAL）对苯丙氨酸（Phe）具有强烈的催化作用。本研究探讨了苯丙酮尿症（PKU）患者口服PAL的可能性。在临床检查中，1例PKU患者分别给予100 U、300 U、600 U和50/kg， Phe为50 mg/kg。血液中Phe水平的增加与单独使用Phe引起的血液中Phe水平的增加几乎相同。但是，当50u /kg的PAl中添加50mg /kg的Phe时，血液中Phe水平的增量明显低于单独使用Phe的增量。另一例PKU患者分别饲喂乳清蛋白1 mg/kg，同时饲喂丝素蛋白中含有PAL 30片，PAL和Empinase分别含有PAL和Empinase。血液Phe水平的模式与单独乳清没有什么不同。他还接受了长期服用PAL和膳食的测试。每餐分别添加24 mg/kg/天的Phe、30T和丝素蛋白中含有的PAL。PAl对血清Phe水平的影响在10天内未见。我们还在豚鼠身上研究了PAl的作用。将上腔静脉（SVC）和门静脉（PV）切开，用含或不含PAL的苯丙氨酸和含苯丙氨酸的肽灌注小肠。SVC和PV中的Phe水平没有明显的增加，而pal则没有明显的增加。当测试多肽时，PAL对SVC和PV中的Phe水平没有任何影响。从本研究中，我们无法得到口服PAL配合餐治疗PKU患者是否有效的结果。

Phenylalanine-ammonia-lyase (PAL) strongly catalyses phenylalanine (Phe) to cynnamate. The possibility of oral administration of PAL with mean as a treatment of phenylketonuria (PKU) was studied.In clinical examination, a patient with PKU was administered 100 U, 300 U, 600 U and 50/kg, respectively, with 50 mg/kg of Phe. The increase of Phe levels in blood were almost same as the increase of blood Phe levels which induced by Phe alone. But, when 50 U/kg of PAl was loaded with 50 mg/kg of Phe, the increments of Phe levels in blood was significantly low as compared with that generated with Phe alone. Another patient with PKU was fed 1 mg/kg of Whey-protein with 30 tablets of PAL included in fibroin and the PAL and Empinase, respectively. The patterns of blood Phe levels were not different with that of Whey alone. He was also tested long-term administration of PAL with meals. The meals contained 24 mg/kg/day of Phe. 30T and PAL included in fibroin were given at each meal. The effect of PAl on serum Phe levels was not seen during 10 days.We also investigated the effect of PAl with guinea pig. Superior vena cava (SVC) and portal vein (PV) were canurated and small intestine was perfused by Phe and peptids contained Phe with or without PAL. When sufficient PAL was included in the test solution with Phe. The Phe levels in SVC and PV were not so much increase as PAL-free. When peptides were tested, PAL did not show any effect on the Phe levels in SVC and PV.From this study, we could not get a result that oral administration of PAL with meal was effective to treat patient with PKU.