Search results for "Receptor"
showing 10 items of 6990 documents
Thermodynamics of the interaction between the spike protein of severe acute respiratory syndrome- coronavirus-2 and the receptor of human angiotensin…
2020
Since the end of 2019, the coronavirus SARS-CoV-2 has caused more than 180,000 deaths all over the world, still lacking a medical treatment despite the concerns of the whole scientific community. Human Angiotensin-Converting Enzyme 2 (ACE2) was recently recognized as the transmembrane protein serving as SARS-CoV-2 entry point into cells, thus constituting the first biomolecular event leading to COVID-19 disease. Here, by means of a state-of-the-art computational approach, we propose a rational evaluation of the molecular mechanisms behind the formation of the complex and of the effects of possible ligands. Moreover, binding free energy between ACE2 and the active Receptor Binding Domain (RB…
Description of a Simple, Specific, and Sensitive Test for the Detection of Detergent-Solubilized C3b Receptor
1981
Abstract The C3b receptor was isolated from detergent-solubilized human erythrocyte membranes by a previously described technique (1). The receptor glycoprotein was shown to enhance EAC14oxy23b rosette formation with Raji lymphoblastoid cells. This provided a specific and sensitive test to detect the solubilized C3b receptor either in crude or highly purified form. The property of the C3b receptor tested by this assay appears to be analogous to properties of β1H.
CATs, a family of three distinct mammalian cationic amino acid transporters
1996
Three related mammalian carrier proteins that mediate the transport of cationic amino acids through the plasma membrane have been identified in murine and human cells (CAT for cationic amino acid transporter). Models of the CAT proteins in the membrane suggest they have 12 or 14 transmembrane domains connected by short hydrophilic loops and intracellular N- and C-termini. The transport activity of the CAT proteins is sensitive to trans-stimulation and independent of the presence of sodium ions. These features agree with the behaviour of carrier proteins mediating facilitated diffusion. The three CAT proteins, CAT-1, CAT-2A and CAT-2(B) are encoded by two different genes (CAT-1 and CAT-2). C…
Understanding the affinity of bis-exTTF macrocyclic receptors towards fullerene recognition
2019
A new series of fullerene receptors based on exTTF macrocycles with alkyl ether chains of increasing length is reported. The novel macrocyclic receptors are able to favourably interact with fullerene C60 through a synergistic combination of π–π, CH⋯π and n⋯π noncovalent interactions. We identify that the highest affinity towards C60 recognition is achieved for the host with the tightest fit; that is, the smallest receptor with a cavity large enough to host the buckyball inside (log Ka = 5.2 in chlorobenzene at 298 K). However, besides this expected observation, theoretical calculations evidence that the most stable self-assembling configuration corresponds for all the receptors to an outsid…
Molecular Design of the Cαβ Interface Favors Specific Pairing of Introduced TCRαβ in Human T Cells
2008
Abstract A promising approach to adoptive transfer therapy of tumors is to reprogram autologous T lymphocytes by TCR gene transfer of defined Ag specificity. An obstacle, however, is the undesired pairing of introduced TCRα- and TCRβ-chains with the endogenous TCR chains. These events vary depending on the individual endogenous TCR and they not only may reduce the levels of cell surface-introduced TCR but also may generate hybrid TCR with unknown Ag specificities. We show that such hybrid heterodimers can be generated even by the pairing of human and mouse TCRα- and TCRβ-chains. To overcome this hurdle, we have identified a pair of amino acid residues in the crystal structure of a TCR that …
How Glutamate Is Managed by the Blood-Brain Barrier
2016
A facilitative transport system exists on the blood brain barrier (BBB) that has been tacitly assumed to be a path for glutamate entry to brain. But glutamate is a non-essential amino acid whose brain content is much greater than plasma, and studies in vivo show that glutamate does not enter brain in material quantities except in those small regions with fenestrated capillaries (circumventricular organs). The situation became understandable when luminal (blood facing) and abluminal (brain facing) membranes were isolated and studied separately. Facilitative transport of glutamate and glutamine exist only on the luminal membranes whereas Na+-dependent transport systems for glutamate, glutamin…
Xenograft rejection in marine sponges. Isolation and purification of an inhibitory aggregation factor from Geodia cydonium.
1981
In sponges there exists a graft rejection mechanism in which an inhibitory aggregation factor is involved. The inhibitory aggregation factor has been isolated from a culture medium containing dissociated cells of the sponge Geodia cydonium. Using ion-exchange and gel fractionation the factor was purified and shown to be electrophoretically pure. The factor has a molecular weight of 27000 and was characterized as a glycoprotein. The activity of the inhibitory aggregation factor was not affected by heat treatment, but treatment with trichloroacetic acid resulted in the irreversible loss of activity. The inhibitory aggregation factor affects the aggregation-factor-mediated reaggregation of dis…
Glycoconjugate expression and cartilage development of the cranial skeleton.
1998
Only few detailed investigations have focused on the glycobiology of cranial development. The functional elements in most inductive and morphogenetic processes are not individual cells, but rather collectives of interacting populations and extracellular matrix components that give rise to specific tissues and organs. Experimental evidence strongly suggests that sugar chains not only confer morphological characteristics. Complex carbohydrate molecules and their corresponding receptors are involved in recognition processes decoding biological information during cranial morphogenesis. The distribution patterns of glycoconjugates are highly dynamic and show a clear correlation with characterist…
New molecular catalysts for ATP cleavage. Criteria of size complementarity
2000
The interaction of the cyclophane receptor 2,5,8,11,14,17-hexaaza[18]metacyclophane (L) with the nucleotides ATP, ADP and AMP is described. L yields one of the largest rate enhancements for hydrolytic ATP cleavage observed in macrocyclic polyamines. The process is specific for the formation of ADP and involves a high degree of geometrical complementarity between host and guest species. The analogue compound 24-hydroxy-2,5,8,11,14,17-hexaaza[18]metacyclophane (L11) shows also a high degree of ATP activation. However, in this case deprotonation of the hydroxy group results in almost complete quenching of the ATPase activity above pH 7.0.
Synthesis and pharmacological evaluation of enantiomerically pure endo-configured KOR agonists with 2-azabicyclo[3.2.1]octane scaffold
2021
Conformationally restricted bicyclic KOR agonists 10 with an endo configured amino moiety were synthesized to analyze the bioactive conformation of conformationally flexible KOR agonists such as 2-5. A seven-step, chiral pool synthesis starting with (S)-configured 4-oxopiperidine-2-carboxylate 13 was developed. cis and trans configured diesters 12 were obtained in a 3:1 ratio via hydrogenation of the α,β unsaturated ester 14. After establishment of the bicyclic scaffold, a diastereoselective reductive amination of ketone 11 provided exclusively the endo configured bicyclic amines 10a,b. The 3:1 mixtures of enantiomers were separated by chiral HPLC, respectively, leading to enantiomerically …