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  1. Enzymatic Catalysis

    Linked via "histidine"

    Acid-Base Catalysis
    This strategy involves the transfer of protons ($\text{H}^+$) to or from the substrate or an intermediate. Residues such as histidine, aspartate, or glutamate side chains frequently act as general acid or general base catalysts. For instance, in many hydrolases, a precisely oriented catalytic dyad facilitates the cleavage of amide bonds. If the active site residue acts as a base, it abstrac…

  2. Enzymatic Catalysis

    Linked via "histidine"

    Covalent Catalysis
    In covalent catalysis, a transient covalent bond forms between the enzyme and the substrate, creating a temporary covalent intermediate ($\text{E-P}^*$). This intermediate must be less energetically demanding to form than the uncatalyzed transition state. Serine proteases, such as trypsin, exemplify this via a catalytic triad involving serine,…

  3. Methylation

    Linked via "histidine"

    Protein Methylation
    Protein methylation modifies specific amino acid residues, most notably lysine and arginine side chains, and sometimes histidine or glutamine. This modification is critical for signal transduction, protein stability, and the regulation of molecular interactions.
    | Residue Modified | Type of Methylation | Functional Consequence (Observed) | Enzyme Class |

  4. Protein Denaturation

    Linked via "histidine"

    Urea and Guanidinium Chloride (GdnHCl): These compounds are highly effective chaotropic agents. Their mechanism is thought to involve direct interaction with the peptide backbone via hydrogen bonding, which competes with the internal hydrogen bonds of the protein. GdnHCl is generally regarded as more potent than urea, often showing a higher linear dependency on concentration for unfolding equilibrium constants.
    Strong Acids and Bases:…

  5. Salt Bridge

    Linked via "Histidine"

    | Aspartate-Lysine | $0.35 \pm 0.05$ | $-4.2$ | $0.11$ |
    | Glutamate-Arginine | $0.41 \pm 0.07$ | $-5.9$ | $0.09$ |
    | Histidine-Aspartate | $0.31 \pm 0.04$ | $-2.8$ | $0.14$ |
    | Cysteine (Protonated)–Cysteine (Deprotonated) | $0.45 \pm 0.06$ | $-1.5$ (Apparent) | $0.22$ |