The His-x-Asp (HxD) motif is one of the most conserved structural components of the catalytic core of protein kinases; however, the functional role of the conserved histidine is unclear. Here we report that replacement of the HxD-histidine with Arginine or Phenylalanine in Aurora A abolishes both the catalytic activity and auto-phosphorylation, whereas the Histidine-to-tyrosine impairs the cata...

Whether oxidative deamination is the favored initial step in the catabolism of histidine, as may be the case with many of the amino acids, is open to question. The supporting evidence of Krebs (1) is less striking with r,-histidine than with most other natural amino acids. Kidney slices yielded somewhat more ammonia in the presence of histidine and oxygen than in the absence of either, and live...

Objectives/Goals Human mast cells produce histidine decarboxylase, which catalyzes the histidine decarboxylation reaction, converting histidine to histamine. This reaction causes histamine to attach to receptors in the immune system, resulting in allergy symptoms. Current treatments for hay fever include antihistamines, a class of chemicals that prevent histamine from attaching to these recepto...

External stimuli are powerful tools that naturally control protein assemblies and functions. For example, during viral entry and exit changes in pH are known to trigger large protein conformational changes. However, the molecular features stabilizing the higher pH structures remain unclear. Here we elucidate the conformational change of a self-assembling peptide that forms either small or large...

The substitution of 1-methyl-l-histidine for the histidine heme ligands in a de novo designed four-alpha-helix bundle scaffold results in conversion of a six-coordinate cytochrome maquette into a self-assembled five-coordinate mono-(1-methyl-histidine)-ligated heme as an initial maquette for the dioxygen carrier protein myoglobin. UV-vis, magnetic circular dichroism, and resonance Raman spectro...

A multi-site speciation model facilitates double-histidine motif labelling efficiency optimisation for pulse dipolar EPR measurements. Results suggest affinities differing by a factor of 10 between an ?-helical and ?-sheet motif.

Oxidation of histidine by (1)O2 is an important process associated with oxidative damage to proteins during aging, diseases and photodynamic therapy of tumors and jaundice, and photochemical transformations of biological species in the troposphere. However, the oxidation mechanisms and products of histidine differ dramatically in these related environments which range from the gas phase through...

currently cancer is considered as one of the main factors of mortality globally. many chemicals in our environment can cause genetic mutations and are potentially responsible for millions of cancer-related deaths. nowadays the scientists are looking for food materials which can potenthially prevent the cancer occurrence. the purpose of this research is to examine antimutagenicity and anticancer...

glucose 6-phosphate dehydrogenase (g6pd) was purified from streptomyces aureofaciens and inactivated with butanedione and diethylpyrocarbonate. incubation of the enzyme with butanedione resulted in a rapid activity loss (80%) within 5 min, followed by a slow phase using a molar ratio to enzyme concentration of 100. fluorescence studies showed a conformational change in the butanedione-modified ...