Question

The deamination of glutamate with GLUTAMATE DEHYDROGENASE is called OXIDATIVE DEAMINATION.

1. What are the products of glutamate oxidative deamination? and what cofactor(s) is/are involved?

2. What α-ketoacid/amino acid pair connects glycolysis and amino acid metabolism?

Answer 1

Oxidative deamination is a form of deamination that generates α-keto acids and other oxidized products from amine-containing compounds, and occurs only in the liver. Oxidative deamination is an important step in the catabolism of amino acids, generating a more metabolizable form of the amino acid, and also generating ammonia as a toxic byproduct. The ammonia generated in this process can then be neutralized into urea via the urea cycle.

1.Glutamate + H2O in the presence of Glutamate dehydrogenase (in mitochondria ) it forms - Ketoglutarate and NH4+ (ammonium ion ) and NAD is reduced. Glutamate dehydrogenase requires NAD+ or NADP+ as cofactor. thjis is the enzyme that has the specificity for both types of cofactors.

Glutamate dehydrogenase (GDH) is a mitochondrial enzyme that is normally activated by leucine and ADP and inhibited by GTP and ATP. GDH increases the oxidative deamination of glutamate to α-ketoglutarate and ammonia, thereby raising the ATP/ADP ratio, which results in closure of the KATP channel and release of insulin.

2.Interaction between glycolysis and amino acid metabolism.

. A point of interaction between glycolysis and glutaminolysis is PGM with its substrate 3-phosphoglycerate and its product 2-phosphoglycerate. 3-Phosphoglycerate is the precursor for serine synthesis, whereas 2-phosphoglycerate is the product of serine degradation. The amino group for serine synthesis derives from the glutaminolytic intermediate glutamate. Pyruvate as acceptor of the amino group of serine can derive from glycolysis or glutaminolysis. It is required for alanine synthesis but also for the lactate dehydrogenase reaction, which recycles NAD required by GAPDH.