Histidine control

Fig. 3. a) First order plot of oxygen uptake in the Methylene-blue (MB)-sensitized photooxidation of GA 8.4 pM and 1.3 mM histidine (control) in phosphate buffer pH 7. b) Percentage radical scavenging activity for the control molecule Trolox and GA at pH 7.4 in phosphate buffer 10 mM (hydroxyl radical) and pH 10 in sodium carbonate buffer 50 mM (anion superoxide radical). 

Neurotransmitter and biogenic amine derived from the amino acid histidine synthesized in hypothalamic tuber-omamillary neurons (TMN) to maintain wakefulness, feeding rhythms, energy balance, neuroendocrine autonomic control, and memory functions prominent immu-nomodulator and proinflammatory signal released from mast cells in response to allergic reactions or tissue damage. 

Because of the exposed histidine ligands of the [2Fe-2S] cluster, the Rieske is capable of binding quinones in a redox-dependent manner. The variation of the hydrogen bond strength and of the electrostatic properties will control the movement of the catalytic domain of the Rieske protein. Therefore, the function depends on the unique structural and electrochemical properties of the Rieske cluster. 

How is the affinity of Rieske clusters for the binding of ligands (e.g., semiquinone) controlled, and what is the role of the exposed histidine residues ... 

Fig. 15 Amino acid sequences of artificial extracellular matrix (aECM) proteins. Each protein contains a TV tag, a histidine tag, a cleavage site, and elastin-like domains with lysine residues for crosslinking. The RGD cell-binding domain is found in aECM 1, whereas aECM 3 contains the CS5 cell-binding domain. aECM 2 and aECM 4 are the negative controls with scrambled binding domains for aECM 1 and aECM 3, respectively. Reprinted from [121] with permission from American Chemical Society, copyright 2004...

E. coli strain BL21(DE3) (F ompT ksdSafra ms ) gal dcm) (Novagen, Madison, WI, USA) was used as a host for recombinant OPH expression. Recombinant plasmids pTOH and pEOH that contain OPH gene fused with hexa-histidine affinity tag under trc and T7 promoter, respectively, as control vectors and pTTOH and pETOH that contain OPH gene fused with Tat signal sequence and hexa-histidine affinity tag under trc and T7 promoter, respectively, were used (Fig. 1). 

Figure 4.8 Reduction of Na/K ATPase activity in isoiated guinea-pig hearts subjected to ischaemia/reperfusion and its prevention by various agents control non-ischaemic hearts (Nl) guinea-pig hearts subjected to global ischaemia for 2 h and subsequently reperfused for 1 h (IR). In other preparations, superoxide dismutase (SOD) 100 U/ml, catalase (CAT) 150 U/ml, dimethylsulphoxide (DMS) 50 mu, histidine (HIS) 10 mu, vitamin E (TOC)...

Lee ES, Shin HJ, Na K et al (2003) Poly(L-histidine)-PEG block copolymer micelles and pH-induced destabilization. J Control Release 90 363-374... 

Specific enzymes control histamine synthesis and breakdown 253 Several forms of histidine decarboxylase may derive from a single gene 254... 

Histamine synthesis in the brain is controlled by the availability of L-histidine and the activity of histidine decarboxylase 254 Histamine is stored within and released from neurons but a neuronal transporter for histamine has not been found 254 In the vertebrate brain, histamine metabolism occurs predominately by methylation 254... 

Histamine synthesis in the brain is controlled by the availability of L-histidine and the activity of histidine decarboxylase. Although histamine is present in plasma, it does not penetrate the blood-brain barrier, such that histamine concentrations in the brain must be maintained by synthesis. With a value of 0.1 mmol/1 for L-histidine under physiological conditions, HDC is not saturated by histidine concentrations in the brain, an observation that explains the effectiveness of large systemic doses of this amino acid in raising the concentrations of histamine in the brain. The essential amino acid L-histidine is transported into the brain by a saturable, energy-dependent mechanism [5]. Subcellular fractionation studies show HDC to be localized in cytoplasmic fractions of isolated nerve terminals, i.e. synaptosomes. 

Parmentier, R., Ohtsu, H., Djebbara-Hannas, Z., Valatx, J. L., Watanabe, T. and Lin, J. S. Anatomical, physiological, and pharmacological characteristics of histidine decarboxylase knock-out mice evidence for the role of brain histamine in behavioral and sleep-wake control. /. Neurosci. 22 7695-7711,2002. 

The total number of cell divisions that take place in the supplemented top agar. This is controlled by the supply of nutrients, in particular, histidine. Rat liver extracts may also supply trace amounts of limiting nutrients, resulting in a slight increase in the spontaneous yield of mutants in the presence of S9 mix. 

Dmb ligand is replaced by His to generate the His-on conformation (Figure 15.8B). This His residue is part of a catalytic triad which controls the coordination state of cobalt (His-on/ His-off) by modulating the protonation state of the histidine. 

Fig. 3.6. Stereoelectronic control of the cleavage of the tetrahedral intermediate during hydrolysis of a peptide bond by a serine hydrolase. The thin lines represent the reactive groups of the enzyme (serine, imidazole ring of histidine) the thick lines represent the tetrahedral intermediate of the transition state. The full circles are O-atoms open circles are N-atoms. The dotted lines represent H-bonds the thick double arrow indicates an unfavorable dipole-dipole interaction [21]. A (R)-configured N-center B (S)-configured N-center.

The axial ligands of yeast cytochrome c. Histidine 21 and Met 85 respectively, not only contribute to the high positive potential of cytochrome c but also control the electronic distribution in cytochrome c in such a way that charge density is concentrated at the reactive heme edge. 

Polymorphs and solvated crystals is generally observed in pharmacentical indnstry [1], The bioavailability, stability, solnbility, and morphology of the pharmacentical products are very influenced by polymorphs [2-7], therefore the control of the polymorphic crystallization is very important. The crystallization process of polymorphs and solvated crystals is composed of competitive nucleation, growth, and transformation from a meta-stable form to a stable form [4], Furthermore, the crystallization behavior is influenced by various controlling factors such as temperature, supersaturation, additives and solvents [8], In order to perform the selective crystallization of the polymorphs, the mechanism of each elementary step in the crystallization process and the key controlling factor needs to be elucidated [8], On the other hand, we reported for L-Glutamic acid and L-Histidine system previously [4] that the nucleation and transformation behaviors of polymorphs depend on the molecular stractures. If the relationship between molecular stmcture and polymorphic crystallization behavior is known, the prediction of the polymorphism may become to be possible for the related compound. However, detail in such relationship is not clearly understood. 

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