Kinases that phosphorylate substrate proteins on tyrosine, serine and threonine, play critical roles in all aspects of cell homeostasis and are under intense scrutiny as potential drug targets in a clinical setting. Dysfunctions of protein kinases (and protein phosphatases) are associated with numerous severe pathological states and consequently it is not surprising that the pharmaceutical and ...

BACKGROUND Among the 20 natural amino acids histidine is the most active and versatile member that plays the multiple roles in protein interactions, often the key residue in enzyme catalytic reactions. A theoretical and comprehensive study on the structural features and interaction properties of histidine is certainly helpful. RESULTS Four interaction types of histidine are quantitatively cal...

A single histidine C-2 proton resonance is seen to shift with change in pH in the NMR spectra of horse ferrocytochrome c, as previously found for horse ferricytochrome c (COHEN, J. S., FISHER, W. R., AND SCHECHTER, A. N. (1973) J. Biol. Chem. 249, 1113-1118). The pK, value (6.5) of this histidine residue in the reduced form is almost the same as that (6.4) in the oxidized form, and only a small...

The metabolism of a histidine load after the differential induction of the hepatic histidine catabolic enzymes, histidase, and cytosolic histidine-pyruvate aminotransferase, and the functional significance of these inductions, has been studied in the intact rat and in the isolated perfused rat liver. Histidase was induced by feeding an 80% casein diet, while the aminotransferase (as well as his...

The presence of several naturally occurring amino acids in the serosal bath of toad urinary bladder significantly alters the hydrosmotic response of this tissue to vasopressin. We found that histidine, glutamate, and lysine increase vasopressinstimulated water flow by 75%, 60%, and 43%, respectively. In contrast, alanine did not alter vasopressin-stimulated water flow, whereas glutamine decreas...

The composition of biologically active substances in the aqueous total fraction 95% EtOH extract aerial part Alfredia cernua (L.) Cass. possessing antiamnesic properties was studied using chromatographic and mass-spectrometric methods. amount N-containing compounds found to be 10.63 ± 1.65%. Fifteen amino acids (1.99 0.11%), seven which (0.76 0.012%) were essential included lysine, threonine, v...

A simple and efficient colorimetric method for the naked-eye detection and quantification of histidine in biological fluids was developed based on an indicator-displacement assay (IDA) and the Ni(2+)-histidine affinity pair. In this IDA approach, a commercially available dye, murexide, was used as the indicator and the selective detection of histidine was achieved based on the competition betwe...

In this paper, we describe a simple and sensitive method for the selective detection of histidine by combining Tween 20-capped gold nanoparticles (Tween 20-AuNPs) as aminothiol removers and o-phthaldialdehyde (OPA) as the derivatization reagent. We have shown that Tween 20-AuNPs are capable of removing homocysteine (HCys), glutathione (GSH), and gamma-glutamylcysteine (Glu-Cys) at low pH condit...

Phytochromes are photoreceptors that control many plant light responses. Phytochromes have two carboxyl-terminal structural domains called the PAS repeat domain and the histidine kinase-related domain. These domains are each related to bacterial histidine kinase domains, and biochemical studies suggest that phytochromes are light-regulated kinases. The PAS repeat domain is important for proper ...

The recent findings (1, 2) that I( -)-histidine is not required for the maintenance of nitrogen balance in man prompted us to investigate the metabolic fate of d(+)-histidine in the human. The excretion procedure which we have previously employed (3) for determining the degree of utilization of d-amino acids seemed uniquely suited in this instance in which the nitrogen balance technique would n...