Search results for "affinity"

Structural incorporation of nitrogen into zeolites, and alpos: ab initio molecular orbital calculations on stability and basicity

1998

Ab initio molecular orbital calculations (HF/6-31G*) are used to obtain thermodynamical information on the possibility to form NH-bridging or NH2-terminal groups in amorphous and crystalline materials containing Si–O–Si and Al–O–P structures, such as for instance, zeolites and aluminophosphates. We have employed dimeric model clusters Si–O–Si and Al–O–P which contain NH2-terminal groups or an oxygen atom substituted by a NH bridging unit. The Bronsted basicity and the softness–hardness of these structures have been determined using the proton affinity and the HOMO energy, respectively. The obtained results indicate that for both Si–O–Si and Al–O–P linkages and from a thermodynamic standpoin…

Activation of the p75 neurotrophin receptor through conformational rearrangement of disulphide-linked receptor dimers.

2009

Ligand-mediated dimerization has emerged as a universal mechanism of growth factor receptor activation. Recent structural studies have shown that neurotrophins interact with dimers of the p75 neurotrophin receptor (p75NTR), but the actual mechanism of receptor activation has remained elusive. Here we show that p75NTR forms disulphide-linked dimers independently of neurotrophin binding through the highly conserved Cys257 in its transmembrane domain. Mutation of Cys257 abolished neurotrophin-dependent receptor activity but did not affect downstream signaling by the p75NTR/NgR/Lingo-1 complex in response to MAG, indicating the existence of distinct, ligand-specific activation mechanisms for p7…

Production of biologically active recombinant avidin in baculovirus-infected insect cells

1997

Abstract An efficient lepidopteran insect cell system was established for the expression of a recombinant form of chicken egg-white avidin. The gene product was obtained in both secreted and intracellular forms, and biologically active recombinant avidin was isolated using affinity chromatography on an iminobiotin–agarose column. Similar to the known quaternary structure of the native egg-white protein, the purified recombinant protein was glycosylated and assembled mainly into tetramers. Like native avidin, the recombinant tetramer also exhibited a high level of thermostability, and was further stabilized upon binding biotin. The biotin-binding and structural properties of the recombinant …

Thin-layer affinity chromatography in analysis of protein-ligand affinity.

1996

The human brain hexacoordinated neuroglobin three-dimensional structure

2004

Neuroglobin, mainly expressed in vertebrate brain and retina, is a recently identified member of the globin superfamily. Augmenting O2 supply, neuroglobin promotes survival of neurons upon hypoxic injury, potentially limiting brain damage. In the absence of exogenous ligands, neuroglobin displays a six-coordinated heme. O2 and CO bind to the heme-iron, displacing the endogenous HisE7 heme distal ligand. Hexacoordinated human neuroglobin displays a classical globin fold, adapted to host the reversible bis-histidyl heme complex, and an elongated protein matrix cavity, held to facilitate O2 diffusion to the heme. The structure of neuroglobin suggests that the classical globin fold is endowed w…

Proteins participating to the post-transcriptional regulation of the mitochondrial cytochrome c oxidase subunit IV via elements located in the 3′UTR

2009

Abstract In developing rat brain cytochrome c oxidase subunit IV (COXIV) expression is also regulated at post-transcriptional level and two 3′UTR-COXIV RNA-binding factors have been identified. Here, we report the enrichment and identification of the factors from just born rat brains by affinity chromatography of biotinylated 3′UTR-COXIV RNA–protein complexes on streptavidin-conjugated paramagnetic particles. We successfully isolated two main proteins of about 86 and 42 kDa, whose sequences were highly attributable to Hsp90 and Actin. The purified proteins maintain RNA-binding ability and specificity for COXIV messenger and, interacting with the 3′UTR, then could negatively modulate mRNA tr…

Purification and partial characterization of a lectin protein complex, the clathrilectin, from the calcareous sponge Clathrina clathrus

2016

Carbohydrate-binding proteins were purified from the marine calcareous sponge Clathrina clathrus via affinity chromatography on lactose and N-acetyl glucosamine- agarose resins. Proteomic analysis of acrylamide gel separated protein subunits obtained in reducing conditions pointed out several candidates for lectins. Based on amino- acid sequence similarity, two peptides displayed homology with the jack bean lectin Concanavalin A, 
 including a conserved domain shared by proteins in the L-type lectin superfamily. An N-acetyl glucosamine - binding protein complex, named clathrilectin, was further purified via gel filtration chromatography, bioguided with a diagnostic rabbit erythrocyte haemag…

An organelle-specific protein landscape identifies novel diseases and molecular mechanisms.

2016

Cellular organelles provide opportunities to relate biological mechanisms to disease. Here we use affinity proteomics, genetics and cell biology to interrogate cilia: poorly understood organelles, where defects cause genetic diseases. Two hundred and seventeen tagged human ciliary proteins create a final landscape of 1,319 proteins, 4,905 interactions and 52 complexes. Reverse tagging, repetition of purifications and statistical analyses, produce a high-resolution network that reveals organelle-specific interactions and complexes not apparent in larger studies, and links vesicle transport, the cytoskeleton, signalling and ubiquitination to ciliary signalling and proteostasis. We observe sub…

Bohr-effect and buffering capacity of hemocyanin from the tarantula E. californicum.

2003

A previous report showed that binding of oxygen to the 24-meric hemocyanin from E. californicum does not correlate linearly with the release of protons as known from hemoglobin. However, this unusual complex phenomenological observation could not be explained at that time. Here, I present a full analysis of the thermodynamic coupling between protons and oxygen for the 24-meric tarantula hemocyanin in Ringer-solution based on the Nested-MWC-model. A strategy is presented which allows to reduce the number of free parameters when fitting the model to the data by including explicitly the equilibrium constants for binding of protons to the different conformations. The results show that the Neste…

Enantiomeric quality control of antihistamines in pharmaceuticals by affinity electrokinetic chromatography with human serum albumin as chiral select…

2007

The present paper deals with the enantiomeric separation of six antihistaminic enantiomers by affinity electrokinetic chromatography (AEKC)-partial filling technique using human serum albumin (HSA) as chiral selector. A multivariate optimization approach of the most critical experimental variables in enantioresolution, running pH, HSA concentration and HSA plug length (SPL) was carried out since there are interactions between variables that could not be considered in an univariate optimization. The estimated and experimental resolution values obtained for antihistaminic enantiomers varied from 1.13 (for orphenadrine) to 2.15 (for brompheniramine). The optimum experimental conditions for ena…