scholarly journals Inhibition of the specific binding of human lactotransferrin to human peripheral-blood phytohaemagglutinin-stimulated lymphocytes by fluorescein labelling and location of the binding site

1991 ◽  
Vol 276 (3) ◽  
pp. 733-738 ◽  
Author(s):  
D Legrand ◽  
J Mazurier ◽  
P Maes ◽  
E Rochard ◽  
J Montreuil ◽  
...  
Keyword(s):  
Binding Site ◽  
Receptor Binding ◽  
Peripheral Blood ◽  
Human Peripheral Blood ◽  
Specific Binding ◽  
Peripheral Blood Lymphocytes ◽  
Receptor Binding Site ◽  
Terminal Domain ◽  
Total Fluorescence ◽  
Domain I

Labelling of human lactotransferrin with fluorescein 5′-isothiocyanate (FITC) in an equimolar ratio inhibits the binding of the protein to phytohaemagglutinin-activated human peripheral-blood lymphocytes. Therefore it can be assumed that FITC reacts at, or near, the receptor-binding site. Three FITC-labelled peptides have been purified from a tryptic digest of the FITC-labelled lactotransferrin. The determination of their amino acid sequence and their localization on the primary structure of the protein permitted the identification of two FITC-accessible areas in the N-terminal lobe and one in the C-terminal lobe. In fact, only 10% of the total FITC was conjugated to one lysine residue (Lys579) of the C-terminal lobe, whereas most (80%) of the FITC was conjugated to three close lysine residues [Lys263 (65% of total fluorescence), Lys280 and Lys282 (15% of total fluorescence)] located in beta-turn structures, of the N-terminal domain I of human lactotransferrin. The results obtained show that the receptor-binding site should be located in the vicinity of the FITC-accessible Lys263, Lys280 and Lys282, and corroborate our preliminary results reporting the involvement of the N-terminal domain I in the binding of human lactotransferrin to mitogen-stimulated lymphocytes [Rochard, Legrand, Mazurier, Montreuil & Spik (1989) FEBS Lett. 255, 201-204]. In any case, FITC labelling is not suitable for studying the binding of lactotransferrin to activated lymphocytes and its use may lead to erroneous interpretations of cell binding experiments.

scholarly journals A highly conserved surface loop in the C-terminal domain of ovotransferrin (residues 570-584) is remote from the receptor-binding site

1990 ◽  
Vol 266 (2) ◽  
pp. 393-398 ◽  
Author(s):  
A B Mason ◽  
S A Brown ◽  
W R Church
Keyword(s):  
Binding Site ◽  
Receptor Binding ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Polyclonal Antibodies ◽  
Receptor Binding Site ◽  
Cellular Receptors ◽  
Phase Synthesis ◽  
Surface Loop ◽  
Terminal Domain

A peptide corresponding to a surface loop in the C-terminal domain of chicken ovotransferrin (residues 570-584) was made by solid-phase synthesis and used to immunize rabbits. A 15-amino acid-residue disulphide-linked loop occurs in both domains of all five transferrins for which the sequence is available and lies on the opposite side of the iron-binding site from the interdomain cleft. Polyclonal antibodies to the peptide were specific for non-reduced holo-ovotransferrin and the C-terminal domain, as shown by e.l.i.s.a. and immunoblotting. The antibody did not inhibit binding of ovotransferrin to receptors on chick-embryo reticulocytes but was able to bind ovotransferrin bound to the cellular receptors at 0 degree C. The loop composed of residues 570-584 appears to be remote from the transferrin receptor-binding site.

scholarly journals Crystal Structure of a Chimeric Receptor Binding Protein Constructed from Two Lactococcal Phages

2009 ◽  
Vol 191 (10) ◽  
pp. 3220-3225 ◽  
Author(s):  
Marina Siponen ◽  
Silvia Spinelli ◽  
Stéphanie Blangy ◽  
Sylvain Moineau ◽  
Christian Cambillau ◽  
...  
Keyword(s):  
Binding Site ◽  
Receptor Binding ◽  
Domain Adaptation ◽  
Host Recognition ◽  
Diverse Population ◽  
Positive Bacterium ◽  
Receptor Binding Site ◽  
Terminal Domain ◽  
Linker Domain ◽  
Slight Displacement

ABSTRACT Lactococcus lactis, a gram-positive bacterium widely used by the dairy industry to manufacture cheeses, is subject to infection by a diverse population of virulent phages. We have previously determined the structures of three receptor binding proteins (RBPs) from lactococcal phages TP901-1, p2, and bIL170, each of them having a distinct host range. Virulent phages p2 and bIL170 are classified within the 936 group, while the temperate phage TP901-1 is a member of the genetically distinct P335 polythetic group. These RBPs comprise three domains: the N-terminal domain, binding to the virion particle; a β-helical linker domain; and the C-terminal domain, bearing the receptor binding site used for host recognition. Here, we have designed, expressed, and determined the structure of an RBP chimera in which the N-terminal and linker RBP domains of phage TP901-1 (P335) are fused to the C-terminal RBP domain of phage p2 (936). This chimera exhibits a stable structure that closely resembles the parental structures, while a slight displacement of the linker made RBP domain adaptation efficient. The receptor binding site is structurally indistinguishable from that of native p2 RBP and binds glycerol with excellent affinity.

scholarly journals Potent sialic acid inhibitors that target influenza A virus hemagglutinin

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yu-Jen Chang ◽  
Cheng-Yun Yeh ◽  
Ju-Chien Cheng ◽  
Yu-Qi Huang ◽  
Kai-Cheng Hsu ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Antiviral Activity ◽  
Binding Site ◽  
Influenza A Virus ◽  
Receptor Binding ◽  
Influenza A ◽  
The United States ◽  
Ligand Complex ◽  
Receptor Binding Site ◽  
Computational Strategy

AbstractEradicating influenza A virus (IAV) is difficult, due to its genetic drift and reassortment ability. As the infectious cycle is initiated by the influenza glycoprotein, hemagglutinin (HA), which mediates the binding of virions to terminal sialic acids moieties, HA is a tempting target of anti-influenza inhibitors. However, the complexity of the HA structure has prevented delineation of the structural characterization of the HA protein–ligand complex. Our computational strategy efficiently analyzed > 200,000 records of compounds held in the United States National Cancer Institute (NCI) database and identified potential HA inhibitors, by modeling the sialic acid (SA) receptor binding site (RBS) for the HA structure. Our modeling revealed that compound NSC85561 showed significant antiviral activity against the IAV H1N1 strain with EC50 values ranging from 2.31 to 2.53 µM and negligible cytotoxicity (CC50 > 700 µM). Using the NSC85561 compound as the template to generate 12 derivatives, robust bioassay results revealed the strongest antiviral efficacies with NSC47715 and NSC7223. Virtual screening clearly identified three SA receptor binding site inhibitors that were successfully validated in experimental data. Thus, our computational strategy has identified SA receptor binding site inhibitors against HA that show IAV-associated antiviral activity.

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