The two amino acids in this group are aspartic acid and glutamic acid. Each has a carboxylic acid on its side chain that gives it acidic (proton-donating) properties. In an aqueous solution at physiological pH, all three functional groups on these amino acids will ionize, thus giving an overall charge of −1. In the ionic forms, the amino acids are called aspartate and glutamate.
The side chains of aspartate and glutamate can form ionic bonds (“salt bridges”), and they can also function as hydrogen bond acceptors. Many proteins that bind metal ions (“metalloproteins”) for structural or functional purposes possess metal-binding sites containing aspartate or glutamate side chains or both. Free glutamate and glutamine play a central role in amino acid metabolism. Glutamate is the most abundant excitatory neurotransmitter in the central nervous system.
The-linking-of-atoms-in-a-peptide-bondThe linking of atoms in a peptide bond.[Credits : Encyclopædia Britannica, Inc.]
Portion-of-polynucleotide-chain-of-deoxyribonucleic-acid-The-inset-showsPortion of polynucleotide chain of deoxyribonucleic acid (DNA). The inset shows the corresponding …[Credits : Encyclopædia Britannica, Inc.]
Red-blood-cells-trapped-in-a-mesh-of-fibrin-threadsRed blood cells (erythrocytes) trapped in a mesh of fibrin threads. The glycoprotein prothrombin, …[Credits : Eye of Science / Photo Researchers, Inc.]
Family-relationships-in-amino-acid-biosynthesesFigure 10: Family relationships in amino-acid biosyntheses. Components of proteins are underlined. …
General-scheme-of-protein-and-amino-acid-metabolismGeneral scheme of protein and amino acid metabolism.[Credits : Encyclopædia Britannica, Inc.]
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