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Asparagine synthetase uses ATP to activate aspartate, forming β-aspartyl-AMP. Glutamine donates an ammonium group, which reacts with β-aspartyl-AMP to form asparagine and free AMP. [21] The biosynthesis of asparagine from oxaloacetate. In reaction that is the reverse of its biosynthesis, asparagine is hydrolyzed to aspartate by asparaginase ...
Deamidation is a chemical reaction in which an amide functional group in the side chain of the amino acids asparagine or glutamine is removed or converted to another functional group. Typically, asparagine is converted to aspartic acid or isoaspartic acid. Glutamine is converted to glutamic acid or pyroglutamic acid (5-oxoproline).
The anionic carboxylate groups behave as Brønsted bases in most circumstances. [32] Enzymes in very low pH environments, like the aspartic protease pepsin in mammalian stomachs, may have catalytic aspartate or glutamate residues that act as Brønsted acids. Functional groups found in histidine (left), lysine (middle) and arginine (right)
Lysine ball and stick model spinning. Lysine (symbol Lys or K) [2] is an α-amino acid that is a precursor to many proteins.Lysine contains an α-amino group (which is in the protonated −NH + 3 form when the lysine is dissolved in water at physiological pH), an α-carboxylic acid group (which is in the deprotonated −COO − form when the lysine is dissolved in water at physiological pH ...
Aspartic acid was first discovered in 1827 by Auguste-Arthur Plisson and Étienne-Ossian Henry [10] [11] by hydrolysis of asparagine, which had been isolated from asparagus juice in 1806. [12] Their original method used lead hydroxide, but various other acids or bases are now more commonly used instead. [citation needed]
Sites that often undergo post-translational modification are those that have a functional group that can serve as a nucleophile in the reaction: the hydroxyl groups of serine, threonine, and tyrosine; the amine forms of lysine, arginine, and histidine; the thiolate anion of cysteine; the carboxylates of aspartate and glutamate; and the N- and C ...
Several protein residues can be methylated, most notably the positive groups of lysine and arginine. Arginine residues interact with the nucleic acid phosphate backbone and commonly form hydrogen bonds with the base residues, particularly guanine, in protein–DNA complexes. Lysine residues can be singly, doubly and even triply methylated.
Several other amino acids aside from proline are susceptible to hydroxylation, especially lysine, asparagine, aspartate and histidine. Lysine may be hydroxylated on its δ-C atom, forming hydroxylysine (Hyl). [9] Several endogenous proteins contain hydroxyphenylalanine and hydroxytyrosine residues.