scholarly journals Purified meningococcal transferrin-binding protein B interacts with a secondary, strain-specific, binding site in the N-terminal lobe of human transferrin

1999 ◽  
Vol 339 (1) ◽  
pp. 143-149 ◽  
Author(s):  
Ian C. BOULTON ◽  
Andrew R. GORRINGE ◽  
Beatrice GORINSKY ◽  
Mark D. RETZER ◽  
Anthony B. SCHRYVERS ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Binding Site ◽  
Specific Binding ◽  
Serum Transferrin ◽  
Human Serum Transferrin ◽  
Binding Data ◽  
Bovine Sequence ◽  
Transferrin Binding Proteins ◽  
Meningococcal Strain ◽  
Site Binding

Neisseria meningitidis, grown in iron-limited conditions, produces two transferrin-binding proteins (TbpA and TbpB) that independently and specifically bind human serum transferrin (hTF) but not bovine serum transferrin (bTF). We have used surface plasmon resonance to characterize the interaction between individual TbpA and TbpB and a series of full-length human–bovine chimaeric transferrins (hbTFs) under conditions of variable saturation with iron. A comparative analysis of hTF and hbTF chimaera-binding data confirmed that the major features involved in Tbp binding are located in the C-terminal lobe of hTF and that isolated TbpA can recognize distinct sites present in, or conformationally influenced by, residues 598–679. Binding by TbpB was maintained at a significant but decreased level after replacement of the entire hTF C-terminal lobe by the equivalent bovine sequence. The extent of this binding difference was dependent on the meningococcal strain and on the presence of hTF residues 255–350. This indicated that TbpB from strain SD has a secondary, strain-specific, binding site located within this region, whereas TbpB from strain B16B6 does not share this recognition site. Binding of TbpA was influenced primarily by sequence substitutions in the hTF C-terminal lobe, and co-purified TbpA and TbpB (TbpA+B) was functionally distinct from either of its components. The limited divergence between hTF and bTF has been related to observed differences in binding by Tbps and has been used to delineate those regions of hTF that are important for such interactions.

A Density Functional Theory Study of the Iron-Binding Site of Human Serum Transferrin

2004 ◽  
Vol 57 (12) ◽  
pp. 1219 ◽  
Author(s):  
David Rinaldo ◽  
Martin J. Field
Keyword(s):  
Human Serum ◽  
Binding Site ◽  
Conformational Changes ◽  
Metal Binding ◽  
Density Functional ◽  
Release Mechanism ◽  
Serum Transferrin ◽  
Iron Binding ◽  
Iron Release ◽  
Human Serum Transferrin

Human serum transferrin binds ferric ions with high affinity in the blood stream and releases them into cells by a process involving receptor-mediated endocytosis and a decrease in pH. The iron-release mechanism is unclear but protonation events and conformational changes are known to be important. In this study, we investigate properties of the iron-binding site theoretically. Our results suggest that an equatorial histidine could be in its histidinate form when bound to iron at neutral and high pH and that protonation of an axial tyrosine is a key event in iron release. Support for this mechanism from other metal-binding enzymes is also presented.

Calcium and the Fc Receptor on Human Platelets

1987 ◽  
Vol 57 (03) ◽  
pp. 298-301
Author(s):  
William F Clark ◽  
Gerald J M Tevaarwerk ◽  
Bruce D Reid ◽  
Suzanne Hall ◽  
Anita Caveney ◽  
...  
Keyword(s):  
Specific Binding ◽  
Normal Subjects ◽  
Human Platelets ◽  
Fc Receptor ◽  
Normal Male ◽  
Scatchard Analysis ◽  
Normal Female ◽  
Apparent Difference ◽  
Binding Data ◽  
Direct Binding

SummaryWe have described the calcium dependence of the IgG Fc receptor (Fc-R) on human platelets by analyzing the direct binding of radiolabelled Fc fragments, monomers and dimers of IgG. Specific binding to platelets was undetectable at 37° C in a calcium-free preparation but readily detected when calcium was restored. Scatchard analysis of the binding data for the calcium-restored platelets permitted calculation of the available Fc-R and the Ka of binding for the different IgG ligands. The mean Ka of binding for 12 normal subjects varied from 107 to 108 L/M, with an equal receptor number measured by Fc fragments and dimers of IgG, but a lesser amount for monomeric IgG. There was no apparent difference in Fc-R number for platelets from 6 normal male versus 6 normal female subjects.At 4° C binding was detectable for dimers and polymers of IgG in a calcium-free preparation and this was markedly increased with recalcification. Thus, our data are consistent with an Fc receptor population on human platelets whose avidity for binding is significantly enhanced in a calcium-restored medium.

The Structural Landscape of SARS-CoV-2 Main Protease: Hints for Inhibitor Search.

2020 ◽  
Author(s):  
Luigi Leonardo Palese
Keyword(s):  
Comparative Analysis ◽  
Global Health ◽  
Binding Site ◽  
Causative Agent ◽  
Data Set ◽  
Substrate Binding Site ◽  
Global Pandemic ◽  
Main Protease ◽  
Crystallographic Structures ◽  
Structural Aspects

In 2019, an outbreak occurred which resulted in a global pandemic. The causative agent of this serious global health threat was a coronavirus similar to the agent of SARS, referred to as SARS-CoV-2. In this work an analysis of the available structures of the SARS-CoV-2 main protease has been performed. From a data set of crystallographic structures the dynamics of the protease has been obtained. Furthermore, a comparative analysis of the structures of SARS-CoV-2 with those of the main protease of the coronavirus responsible of SARS (SARS-CoV) was carried out. The results of these studies suggest that, although main proteases of SARS-CoV and SARS-CoV-2 are similar at the backbone level, some plasticity at the substrate binding site can be observed. The consequences of these structural aspects on the search for effective inhibitors of these enzymes are discussed, with a focus on already known compounds. The results obtained show that compounds containing an oxirane ring could be considered as inhibitors of the main protease of SARS-CoV-2.

scholarly journals A first-principles study on potential chelation agents and indicators of Alzheimer's disease

RSC Advances ◽  
2020 ◽  
Vol 10 (58) ◽  
pp. 35574-35581
Author(s):  
Bryan Wang ◽  
Xuan Luo
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Human Serum ◽  
Blood Brain Barrier ◽  
First Principles ◽  
Brain Barrier ◽  
Serum Transferrin ◽  
Human Serum Transferrin ◽  
First Principles Study ◽  
Blood Brain

Human-serum transferrin is involved in the transportation of aluminum across the blood–brain barrier.

Phosphate Binding to Isolated Chloroplast Coupling Factor (CF1)

1988 ◽  
Vol 43 (3-4) ◽  
pp. 213-218 ◽  
Author(s):  
Bernhard Huchzermeyer
Keyword(s):  
Atpase Activity ◽  
Binding Site ◽  
Inorganic Phosphate ◽  
Coupling Factor ◽  
Binding Domain ◽  
Atp Binding ◽  
Phosphate Binding ◽  
Chloroplast Coupling Factor ◽  
Single Binding Site ◽  
Site Binding

A single binding site for phosphate was found on isolated chloroplast coupling factor in the absence of nucleotides. In our experiments the phosphate binding site showed a Kd of 170 μᴍ. We did not observe any differences whether the ATPase activity of CF] had been activated or not. If the enzyme was incubated with [γ-32P]ATP the amount of 32P bound per CF1 depended on the pretreatment of the enzyme: In the presence of ADP no ATP or phosphate was bound to CF,. After activation of ATPase activity one mol of ATP per mol CF, was rapidly bound and hydrolyzed while there was a slowly occurring binding of another phosphate without concomitant nucleotide binding. We conclude that there are two different types of phosphate binding observed in our experiments: 1) Inorganic phosphate can be bound by one catalytic site per mol of CF1 2) The γ-phosphate of ATP is able to bind to an ATP binding domain of the enzyme if this domain can exchange substrates with the incubation medium. This ATP binding domain appears to differ from the site binding inorganic phosphate, because at least a portion of the coupling factor contains more than one labelled phosphate during our ATPase tests.

Sign in / Sign up

Export Citation Format

Share Document