Natural ligands

Lead generation natural ligand sereening literature leads... 

Natural ligands Certain unsaturated fatty acids and prostaglandin metabolites... 

Endogenous opioid peptides are the wide variety of endogenous peptides isolated since 1975 which are the natural ligands for the opioid receptors. The peptides... 

Besides classical receptor classes that bind endogenous or naturally occurring ligands and act via prototypical intracellular signaling cascades, a considerable number of transmembrane proteins are referred to as receptors albeit their natural ligands are unknown or they do not... 

The Table shows a great spread in Kd-values even at the same location. This is due to the fact that the environmental conditions influence the partition of plutonium species between different valency states and complexes. For the different actinides, it is found that the Kd-values under otherwise identical conditions (e.g. for the uptake of plutonium on geologic materials or in organisms) decrease in the order Pu>Am>U>Np (15). Because neptunium is usually pentavalent, uranium hexavalent and americium trivalent, while plutonium in natural systems is mainly tetravalent, it is clear from the actinide homologue properties that the oxidation state of plutonium will affect the observed Kd-value. The oxidation state of plutonium depends on the redox potential (Eh-value) of the ground water and its content of oxidants or reductants. It is also found that natural ligands like C032- and fulvic acids, which complex plutonium (see next section), also influence the Kd-value. 

Research into the aquatic chemistry of plutonium has produced information showing how this radioelement is mobilized and transported in the environment. Field studies revealed that the sorption of plutonium onto sediments is an equilibrium process which influences the concentration in natural waters. This equilibrium process is modified by the oxidation state of the soluble plutonium and by the presence of dissolved organic carbon (DOC). Higher concentrations of fallout plutonium in natural waters are associated with higher DOC. Laboratory experiments confirm the correlation. In waters low in DOC oxidized plutonium, Pu(V), is the dominant oxidation state while reduced plutonium, Pu(III+IV), is more prevalent where high concentrations of DOC exist. Laboratory and field experiments have provided some information on the possible chemical processes which lead to changes in the oxidation state of plutonium and to its complexation by natural ligands. 

These studies show the usefulness of relative data for the prediction of plutonium complexation with natural ligands. They... 

The 3D structure of the 2,3-diphosphoglycerate (DPG) complex of hemoglobin (Hb) served to derive simple aromatic dialdehydes that mimic the function of DPG as an allosteric modulator of the oxygen affinity of Hb. Some of the resulting compounds were as active and even more active than DPG, the natural ligand [1-3]. 

Parks DJ et al Bile acids natural ligands for a nuclear orphan receptor. Science 1999 284 1365. 

Bajetto A, Bonavia R, Barbero S, PiccioU P, Costa A, Elorio T, Schettini G (1999) GUal and neuronal cells express functional chemokine receptor CXCR4 and its natural ligand stromal ceU-derived factor 1. J Neurochem 73 2348-2357... 

Cochrane, D., Webster, C., Masih, G., and McCafferty, J. (2000). Identification of natural ligands for SH2 domains from a phage display cDNA library. J. Mol. Biol. 297, 89-97. 

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