scholarly journals Cell-type specific activity of two glucocorticoid responsive units of rat tyrosine aminotransferase gene is associated with multiple binding sites for C/EBP and a novel liver-specific nuclear factor

1991 ◽  
Vol 19 (1) ◽  
pp. 131-139 ◽  
Author(s):  
Thierry Grange ◽  
Jeanne Roux ◽  
Gildas Rigaud ◽  
Raymond Pictet
1987 ◽  
Author(s):  
German B Villanueva ◽  
Konno Sensuke ◽  
John Fenton

A highly purified hirudin with a specific activity of 13, 950 AT units/mg was used in these studies. Investigation of the circular dichroism of hirudin and thrombin showed that the CD spectrum of the thrombin-hirudin complex deviates significantly from additivity towards a less organized structure (i.e. loss of a-helix).A sigmoidal curve, rather than a hyperbolic curve, is generated when the deviation from additivity is plotted against hirudin concentration. This suggests cooperativity of the binding process. At low concentation, aScatchard plot of the data fits intoa straight line clearly indicating one binding site per mole of thrombin.This site binds hirudin with a dissociation constant of 500 nM. However, the data cannot be fitted to a straight line at higher concentration ofhirudin suggesting that hirudin binds also to another site with a different affinity. These results agree with the findings of Stone and Hofsteenge (Biochemistry 25, 4622-4628, 1986) and support the idea that initially hirudin binds at a site distinct from the active site, which then rearranges through a conformational change (detected by CD) to form a tigher complex in which hirudin is also bound to the active site.


2019 ◽  
Vol 19 (24) ◽  
pp. 2239-2253 ◽  
Author(s):  
Paul J. Goldsmith

The N-methyl-D-aspartate receptor (NMDAR) is a member of the ionotropic glutamate receptor (iGluR) family that plays a crucial role in brain signalling and development. NMDARs are nonselective cation channels that are involved with the propagation of excitatory neurotransmission signals with important effects on synaptic plasticity. NMDARs are functionally and structurally complex receptors, they exist as a family of subtypes each with its own unique pharmacological properties. Their implication in a variety of neurological and psychiatric conditions means they have been a focus of research for many decades. Disruption of NMDAR-related signalling is known to adversely affect higherorder cognitive functions (e.g. learning and memory) and the search for molecules that can recover (or even enhance) receptor output is a current strategy for CNS drug discovery. A number of positive allosteric modulators (PAMs) that specifically attempt to overcome NMDAR hypofunction have been discovered. They include various chemotypes that have been found to bind to several different binding sites within the receptor. The heterogeneity of chemotype, binding site and NMDAR subtype provide a broad landscape of ongoing opportunities to uncover new features of NMDAR pharmacology. Research on NMDARs continues to provide novel mechanistic insights into receptor activation and this review will provide a high-level overview of the research area and discuss the various chemical classes of PAMs discovered so far.


1993 ◽  
Vol 58 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Imad Al-Bala'a ◽  
Richard D. Bates

The role of more than one binding site on a nitroxide free radical in magnetic resonance determinations of the properties of the complex formed with a hydrogen donor is examined. The expression that relates observed hyperfine couplings in EPR spectra to complex formation constants and concentrations of each species in solution becomes much more complex when multiple binding sites are present, but reduces to a simpler form when binding at the two sites occurs independently and the binding at the non-nitroxide site does not produce significant differences in the hyperfine coupling constant in the complexed radical. Effects on studies of hydrogen bonding between multiple binding site nitroxides and hydrogen donor solvent molecules by other magnetic resonance methods are potentially more extreme.


The Analyst ◽  
2017 ◽  
Vol 142 (2) ◽  
pp. 302-309 ◽  
Author(s):  
Yanxia Li ◽  
Yiting Chen ◽  
Lu Huang ◽  
BenYong Lou ◽  
Guonan Chen

A kind of protein imprinted over magnetic Fe3O4@Au multifunctional nanoparticles (NPs) with multiple binding sites was synthesized and investigated.


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