Hughes J V, Johnson T C
Biochim Biophys Acta. 1978 Feb 16;517(2):473-85. doi: 10.1016/0005-2787(78)90214-9.
The decrease in the neural polyribosomes produced during hyperphenylalaninemia could not be restored to normal levels by the injection of other single neutral amino acids. All of the neutral amino acids that are transported with phenylalanine were found to produce an alteration of neural polyribosomes similar to that measured with phenylalanine. However, the injection of a balanced mixture of 6 or 7 neutral amino acids could restore the brain polyribosomes to normal states. Although this experimentally induced recovery did not lower brain phenylalanine concentrations, it did restore the acylation levels of methionyl-tRNA, and in particular, the methionyl-tRNA initiator species. This also led to a concomitant stimulation of the elongation rate of brain polypeptide synthesis. A natural recovery of brain polyribosomal levels (occurring 2 h after 1 mg/g phenylalanine is injected) did not appear to represent a real recovery of neural protein metabolism. Phenylalanine concentrations were increased in the brain, the acylation levels of methionyl-tRNA, alanyl-tRNA and the initiator methionyl-tRNA remained altered, and the rate of ribosome translocation was decreased 28%.
高苯丙氨酸血症期间产生的神经多核糖体减少，无法通过注射其他单一中性氨基酸恢复到正常水平。所有与苯丙氨酸一同转运的中性氨基酸，都会使神经多核糖体发生类似苯丙氨酸所测得的改变。然而，注射6种或7种中性氨基酸的平衡混合物，可使脑多核糖体恢复到正常状态。尽管这种实验诱导的恢复并未降低脑中苯丙氨酸的浓度，但确实恢复了甲硫氨酰 - tRNA的酰化水平，尤其是甲硫氨酰 - tRNA起始种类水平。这也导致脑多肽合成延伸速率随之受到刺激。脑多核糖体水平的自然恢复（在注射1mg/g苯丙氨酸后2小时出现）似乎并不代表神经蛋白质代谢的真正恢复。脑中苯丙氨酸浓度升高，甲硫氨酰 - tRNA、丙氨酰 - tRNA以及起始甲硫氨酰 - tRNA的酰化水平仍处于改变状态，核糖体转位速率降低了28%。
