Possible Interaction: Histidine and Imidazole

“H+] in body fluids and the pK of histidine imidazole groups of proteins must be regulated in relation to each other to preserve protein conformation and function.”

“5-HO-isourate was found to be formed as a new compound from uric acid and, e.g., imidazole lactate concentrations increased due to the breakdown of histidine.”

“The changes of emission intensities of the four reactions indicate that the two NH2-containing compounds histidine and histamine) both display much higher reaction rates with 1 than the two compounds without NH2 (DA-histidine and imidazole).”

“Our data suggests that it is the imidazole sidechain of histidine 14 that modulates this interaction and strategies inhibiting this interaction may have therapeutic potential for Alzheimer's disease.”

“The inhibitory effect of histidine was ascribed to the imidazole group and may arise from the formation of a different iron complex or the acceleration of polymerization, dehydration, and insolubilization of the ferric ion by the imidazole nitrogen.”

“… imidazole , the rate constants dramatically increase to 3.1 x 106, and 2.4 x lo6 M-’ s-l for heme fragments (l-… change in the axial coordination group of the heme iron atom in fragments (l-38)H and (l-53)H from histidine 33 (or 26) … peptide.”

“Finally, the intrinsic conformational preferences of histidine , and its NREs on the conformational preferences of adjacent residues, are both shown to be strongly affected by the protonation state of the imidazole ring.”

“The assembly process and the stability of the holo-proteins were strongly influenced by the concentration of added imidazole (mimicking the histidine side-chain), making the attachment of the chromophore via the histidine more likely than via another cysteine of the protein.”

“One can conclude that the protonation of imidazole (pK = 5.9) abolishes the capability of histidine to modulate the oxidative degradation of DNA.”