Characterization of High-Affinity Binding between Gangliosides and Amyloid β-Protein

2001 ◽  
Vol 388 (2) ◽  
pp. 225-230 ◽  
Author(s):  
Toshio Ariga ◽  
Kiyoaki Kobayashi ◽  
Akira Hasegawa ◽  
Makoto Kiso ◽  
Hideharu Ishida ◽  
...  
Keyword(s):  
Amyloid Β ◽  
Affinity Binding ◽  
Amyloid Β Protein ◽  
High Affinity Binding ◽  
High Affinity ◽  
Β Protein

Characterization of a Mode of Specific Binding of Fibrin Monomer through its Amino-Terminal Domain by Macrophages and Macrophage Cell-Lines

1990 ◽  
Vol 63 (02) ◽  
pp. 193-203 ◽  
Author(s):  
John R Shainoff ◽  
Deborah J Stearns ◽  
Patricia M DiBello ◽  
Youko Hishikawa-Itoh
Keyword(s):  
Peritoneal Macrophages ◽  
Affinity Binding ◽  
Macrophage Cell ◽  
High Affinity Binding ◽  
Amino Terminal ◽  
High Affinity ◽  
Terminal Domain ◽  
Weak Binding ◽  
Amino Terminal Domain

SummaryThe studies reported here probe the existence of a receptor-mediated mode of fibrin-binding by macrophages that is associated with the chemical change underlying the fibrinogen-fibrin conversion (the release of fibrinopeptides from the amino-terminal domain) without depending on fibrin-aggregation. The question is pursued by 1) characterization of binding in relation to fibrinopeptide content of both the intact protein and the CNBr-fragment comprising the amino-terminal domain known as the NDSK of the protein, 2) tests of competition for binding sites, and 3) photo-affinity labeling of macrophage surface proteins. The binding of intact monomers of types lacking either fibrinopeptide A alone (α-fibrin) or both fibrinopeptides A and B (αβ-fibrin) by peritoneal macrophages is characterized as proceeding through both a fibrin-specific low density/high affinity (BMAX ≃ 200–800 molecules/cell, KD ≃ 10−12 M) interaction that is not duplicated with fibrinogen, and a non-specific high density/low affinity (BMAX ≥ 105 molecules/cell, KD ≥ 10−6 M) interaction equivalent to the weak binding of fibrinogen. Similar binding characteristics are displayed by monocyte/macrophage cell lines (J774A.1 and U937) as well as peritoneal macrophages towards the NDSK preparations of these proteins, except for a slightly weaker (KD ≃ 10−10 M) high-affinity binding. The high affinity binding of intact monomer is inhibitable by fibrin-NDSK, but not fibrinogen-NDSK. This binding appears principally dependent on release of fibrinopeptide-A, because a species of fibrin (β-fibrin) lacking fibrinopeptide-B alone undergoes only weak binding similar to that of fibrinogen. Synthetic Gly-Pro-Arg and Gly-His-Arg-Pro corresponding to the N-termini of to the α- and the β-chains of fibrin both inhibit the high affinity binding of the fibrin-NDSKs, and the cell-adhesion peptide Arg-Gly-Asp does not. Photoaffinity-labeling experiments indicate that polypeptides with elec-trophoretically estimated masses of 124 and 187 kDa are the principal membrane components associated with specifically bound fibrin-NDSK. The binding could not be up-regulated with either phorbol myristyl acetate, interferon gamma or ADP, but was abolished by EDTA and by lipopolysaccharide. Because of the low BMAX, it is suggested that the high-affinity mode of binding characterized here would be too limited to function by itself in scavenging much fibrin, but may act cooperatively with other, less limited modes of fibrin binding.

Opioid receptors in bovine adrenal medulla

1984 ◽  
Vol 62 (10) ◽  
pp. 1284-1291 ◽  
Author(s):  
Michel Dumont ◽  
Simon Lemaire
Keyword(s):  
Binding Site ◽  
G Protein ◽  
Opioid Receptors ◽  
Opioid Peptides ◽  
Affinity Binding ◽  
Endogenous Opioid ◽  
High Affinity Binding ◽  
High Affinity ◽  
High Affinity Binding Site

Using prototypic ligands for each type of opioid receptors (μ, δ, κ, and σ) as well as compounds derived from each class of endogenous opioid peptides (β-endorphin, enkephalins, and dynorphins), we have undertaken the characterization of adrenomedullary opioid binding sites. The specific binding of [3H]etorphine ([3H]ET) to a membrane preparation of bovine adrenal medulla was greatly increased when the incubation temperature was raised from 22 to 37 °C. Characterization of the opioid binding sites was obtained at 37 °C with [3H]ET (nonspecific opioid ligand), [3H]ethylketocyclazocine ([3H]EKC; κ), [3H]dihydromorphine ([3H]DHM; μ), [3H]-[D-Ala2,D-Leu5]enkephalin ([3H]DADLE; δ), and N-[3H]allylnormetazocine ([3H]SKF-10047; σ) in the absence or presence of blocking agents for cross-reacting receptors. [3H]ET had a high affinity binding site (KD = 0.98 nM) with a Bmax of 119 pmol/g protein. All the other opioid compounds showed biphasic saturation curves with KD ranging from 0.6 to 1.29 nM for the high affinity binding site and from 2.49 to 12.1 nM for the low affinity binding site. The opioid μ-receptor was characterized by the high affinity binding site for [3H]DHM (KD = 1.29 nM; Bmax = 38 pmol/g protein). Blockade of the cross-reacting receptor sites for [3H]EKC, [3H]DADLE, and [3H]SKF-10047 revealed the presence of κ (KD = 0.66 nM; Bmax = 12 pmol/g protein), κ2 (benzomorphan site; KD = 11.1 nM; Bmax = 56 pmol/g protein), δ (KD = 0.67 nM; Bmax = 4.7 pmol/g protein), and σ (KD = 4.54 nM; Bmax = 32 pmol/g protein) opioid receptors. The ability of various opioid ligands to displace the binding of [3H]ET indicates a high potency for (−)-(1R,5R,9R,2″S)-5,9-dimethyl-2′-hydroxy-2-tetrahydrofurfuryl-6,7-benzomorphan hydrogen D-tartrate (MR-2034, a κ-opioid ligand; Ki = 6.2 nM), dihydromorphinone (DHMone; Ki = 6.9 nM), oxymorphone (Ki = 8.6 nM), DADLE (Ki high affinity = 8.4 nM) EKC (Ki = 31.8 nM), SKF-10047 (Ki = 75 nM), and opioid agonists/antagonists. trans-(+)-3,4-Dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide methanesulfonate hydrate (U-50,488H), the most specific κ-agonist, was a poor competitor (Ki = 5150 nM). However, the presence of κ-opioid receptors was supported by the ability of U-50,488H to displace [3H]EKC binding (Ki high affinity = 2.5 nM). The relative potency of various endogenous opioid peptides in displacing [3H]ET binding was as follows: β-endorphin [Formula: see text] dynorphin(1-17) > dynorphin(1-13) > [Arg6,Phe7)Met-enkephalin > Met-enkephalin > Leu-enkephalin. In addition, the presence of a high affinity binding site for dynorphin was demonstrated by the high potency of dynorphin (1-13) to displace [3H]EKC binding (Ki high affinity = 2.3 nM). These data provide further insights into the characterization of adrenal opioid receptors and suggest an in situ physiological role for adrenal opioid peptides.

scholarly journals Isolation and Characterization of Patient-derived, Toxic, High Mass Amyloid β-Protein (Aβ) Assembly from Alzheimer Disease Brains

2009 ◽  
Vol 284 (47) ◽  
pp. 32895-32905 ◽  
Author(s):  
Akihiko Noguchi ◽  
Satoko Matsumura ◽  
Mari Dezawa ◽  
Mari Tada ◽  
Masako Yanazawa ◽  
...  
Keyword(s):  
Alzheimer Disease ◽  
Amyloid Β ◽  
High Mass ◽  
Amyloid Β Protein ◽  
Isolation And Characterization ◽  
Β Protein
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