Pyruvate amino acid α keto acid alanine

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Pyruvate Amino acid α -Keto acid Alanine Aminotransferase H 3 C-C(O)-COO - H 3 C-CH( NH 3 + )-COO - Oxaloacetate Amino acid α -Keto acid Aspartate Aminotransferase - OOC-CH 2 -C(O)-COO - - OOC-CH 2 -CH( NH 3 + )-COO - α -ketoglutarate Amino acid α -Keto acid Glutamate Aminotransferase - OOC-(CH 2 ) 2 -C(O)-COO - - OOC-(CH 2 ) 2 -CH( NH 3 + )-COO -
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Asparagine and Glutamine Glutamine + ATP Glutamate + AMP+ PP i Aspartate Asparagine synthetase - OOC-CH 2 -CH( NH 3 + )-COO - Asparagine H 2 N -C(O)-CH 2 -CH( NH 3 + )-COO - ATP + NH 3 ADP + P i Glutamate Glutamine synthetase - OOC-(CH 2 ) 2 -CH( NH 3 + )-COO - Glutamine H 2 N -C(O)-(CH 2 ) 2 -CH( NH 3 + )-COO -
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Glutamine Synthetase • Metabolic functions of glutamine: - donor of amino group - storage form of ammonia • Control of glutamine synthetase is highly important for nitrogen metabolism. • Mammalian glutamine synthetase is activated by α -ketoglutarate, which is a product of the oxidative deamination of glutamate. • Activated glutamate synthetase decreases concentration of ammonia, a toxic metabolite. This prevents accumulation of ammonia.
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Heme Biosynthesis • Heme, a complex of iron with porphyrin , is a component of many proteins, e.g., hemoglobin, myoglobin, cytochromes. Heme is synthesized in the erythrocytes and in the liver. • All carbon and nitrogen atoms of the heme are derived from acetate and glycine. The heme anabolic pathway involves intermediates δ -aminolevulinic acid (ALA) and porphobilinogen (PBG). • Lead inhibits PBG synthase that converts ALA to PBG, and, by this way, causes accumulation of ALA in the blood. • ALA resembles neurotransmitter δ -aminobutyric acid (GABA). Lead poisoning is often accompanied by the psychosis. ALA: - OOC-CH 2 -CH 2 -C(O)-CH 2 -NH 3 + GABA: - OOC-CH 2 -CH 2 -CH 2 -NH 3 +
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