Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.4.1.2 (glutamate dehydrogenase)
 4,380 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hyperinsulinism-hyperammonemia syndrome (HHS) is a recently identified genetic disorder characterized by hyperinsulinemic hypoglycemia with concomitant hyperammonemia. In patients with HHS, activating mutations in the glutamate dehydrogenase (GDH) gene have been identified. GDH is a key enzyme linking glutamate metabolism with the Krebs cycle and catalyzes the conversion of glutamate to alpha-ketoglutarate. The activity of GDH is controlled by allosteric inhibition by GTP and, so far, all the mutations of HHS patients have been located within the GTP-binding site. Characteristically, GDH from these individuals have therefore normal basal activity in conjunction with a loss of GTP inhibition. In this study, however, we have identified a novel variant GDH in a patient with a more severe form of HHS. The mutation is located outside the GTP-binding site and the patient's GDH shows consistently higher activity, even in the absence of allosteric effectors. These results further support the hypothesis that the activating mutation of GDH is the cause of HHS. The mechanism leading to the activation of GDH, however, is not always related to the loss of GTP inhibition as was originally suggested.
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PMID:Hyperinsulinism-hyperammonemia syndrome caused by mutant glutamate dehydrogenase accompanied by novel enzyme kinetics. 1045 35

Hyperinsulinism-hyperammonemia syndrome is characterized by recurrent and symptomatic hypoglycemias in childhood, secondary to hyperinsulinism associated with mild and asymptomatic hyperammonemia. This syndrome is caused by dominantly expressed mutations of the glutamate dehydrogenase gene (10q23.3). These mutations modify control of enzyme activity and represent the second cause of congenital hyperinsulinism of known genetic etiology. Moreover, this syndrome is the first genetic disorder due to an increase of function in an enzyme of intermediary metabolism to have been identified. We present the case of a 16-month-old boy with symptomatic recurrent hypoglycemias from the end of the first year of life, caused by a de novo mutation in exon 7 (G979A) of the GDH gene, with excellent outcome after diazoxide treatment.
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PMID:[Hyperinsulinism-hyperammonemia syndrome due to a de novo mutation in exon 7 (G979A) of the glutamate dehydrogenase gene with excellent response to diazoxide]. 1553 Mar 24

Congenital hyperinsulinism is a genetic condition causing dysregulation of insulin and results in persistent hypoglycemia. The most common types are sulfonylurea receptor (SUR1), potassium inward rectifying channel (Kir6.2), glutamate dehydrogenase (GDH), and glucokinase (GK), with SUR1 and Kir6.2 being the most prevalent. It is imperative that these infants undergo diagnostic testing, which includes genetic, neonatal fasting study to induce hypoglycemia, glucagon stimulation, and imaging. Once a diagnosis has been made, surgical intervention may be needed to help regulate blood glucose levels. During this diagnostic process and as the infant is undergoing treatment, there may be little concern for the mother's feeding plan. Because human milk is the preferred form of nutrition for all infants, these mothers should receive prenatal counseling regarding the initiation and maintenance of milk supply. Parenteral nutrition may be necessary to maintain blood glucose to support human milk administration and breastfeeding.
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PMID:Congenital hyperinsulinism: exclusive human milk and breastfeeding. 2500 Jan 3

Mammalian glutamate dehydrogenase (GDH) has complex allosteric regulation and the loss of GTP inhibition causes the hyperinsulinism/hyperammonemia syndrome (HHS) where insulin is hypersecreted upon consumption of protein. The archetypical HHS lesion is H454Y and lies in the GTP binding pocket. To better understand the mechanism of HHS, we determined the crystal structure of H454Y. When the bovine GDH crystal structures were minimized to prepare for further computational analysis, unusually large deviations were found at the allosteric NADH binding site due to chemical sequence errors. Notably, 387 lies in an allosteric where several activators and inhibitors bind and should be lysine rather than asparagine. All structures were re-refined and the consequence of this sequence error on NADH binding was calculated using free energy perturbation. The binding free energy penalty going from the correct to incorrect sequence found is +5 kcal/mol per site and therefore has a significant impact on drug development. BROADER AUDIENCE ABSTRACT: Glutamate dehydrogenase is a key enzyme involved in amino acid catabolism. As such, it is heavily regulated in animals by a wide array of metabolites. The importance of this regulation is most apparent in a genetic disorder called hyperinsulinism/hyperammonemia (HHS) where patients hypersecrete insulin upon the consumption of protein. We determined the atomic structure of one of these HHS mutants to better understand the disease and also analyzed an allosteric regulatory site.
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PMID:Glutamate dehydrogenase: Structure of a hyperinsulinism mutant, corrections to the atomic model, and insights into a regulatory site. 3036 18