Developing Synthetic Enzymes to Treat Inborn Errors of Metabolism

项目摘要。 在支链酮酸中观察到的严重、急性和慢性发育和神经系统影响 脱氢酶缺陷型枫树糖浆尿病（BCKD缺陷型MSUD）和异戊酰辅酶A 在新生儿中观察到的脱氢酶缺陷型异戊酸血症（IVD缺陷型IVA）是由于存在 高浓度的亮氨酸、异亮氨酸和缬氨酸。患有这些疾病的患者 通过低蛋白饮食和营养补充来控制他们的病情，这往往是不够的， 很难坚持，并且仍然会导致代谢失调。管理战略包括减少 限制有毒代谢物和底物，促进抗氧化和刺激残留酶 活性沿着氨基酸和酮酸清除途径的活化。即便如此， 病人是穷人，因为他们的照顾者，因为病人需要密切监测，以避免代谢危机 由感染、饮食或其他原因引起。因此，对新的药物存在显著的需求， 可以使婴儿、儿童、青少年和成人受益。这项工作是基于假设，高系统性 使用高活性酶可以降低患者体内有害氨基酸的浓度 例如Pegvaliase如何降低苯丙酮尿症（PKU）患者的苯丙氨酸浓度。这项工作的核心 是一种双重方法的实现，它结合了实验性的定向进化技术， 计算酶设计。

Project Summary. The severe, acute, and chronic developmental and neurological impacts seen in branched chain ketoacid dehydrogenase deficient Maple Syrup Urine Disease (BCKD-deficient MSUD) and isovaleryl‐CoA dehydrogenase deficient Isovaleric Acidemia (IVD-deficient IVA) seen in newborns are due to the presence of high concentrations of leucine, isoleucine, and valine in their system. Patients with these disorders are limited to manage their condition though a low-protein diet and nutrient supplementation, which is often inadequate, difficult to adhere to, and can still lead to metabolic decompensation. Management strategies include reduction and restriction of toxic metabolites and substrates, promotion of anabolism and stimulation of residual enzyme activity along with activation of amino acid and ketoacid scavenging pathways. Even then, the quality of life of patients is poor, as is for their caregivers since patients need to be monitored closely to avoid metabolic crisis precipitated either by infection, diet, or other reasons. Thus, there is significant need for new medications that can benefit infants, children, adolescents, and adults. This work is based on the hypothesis that high systemic concentrations of offending amino acid(s) in patients can be reduced using high activity enzymes, in a manner like how Pegvaliase reduces phenylalanine concentrations in phenylketonuria (PKU) patients. Core to this work is implementation of a twofold approach that combines experimental directed evolution techniques and computations enzyme design.