Developing Synthetic Enzymes to Treat Inborn Errors of Metabolism

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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.