scholarly journals Fluorescent Analogues of FRH Peptide: Cu(II) Binding and Interactions with ds-DNA/RNA

Chemosensors ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 34
Author(s):  
Marta Košćak ◽  
Ivona Krošl ◽  
Biserka Žinić ◽  
Ivo Piantanida
Keyword(s):  
Binding Site ◽  
Free Amino ◽  
Thermal Denaturation ◽  
Rna Binding ◽  
Cation Binding ◽  
Peptide Motif ◽  
Cd Spectra ◽  
Amino Groups ◽  
Highly Sensitive ◽  
Fluorescent Analogues

Four novel peptidoids, derived from the Phe-Arg-His (FRH) peptide motif, were prepared by replacing the histidine heterocycle with triazole and consequent triazole-fluorophore (coumarin) extension and also replacing arginine with less voluminous lysine. So the constructed Phe-Lys-Ala(triazole) (FKA(triazole)) peptidoids bind Cu2+ cations in water with a strong, nanomolar affinity comparable to the parent FRH and its known analogs, demonstrating that triazole can coordinate copper similarly as histidine. Moreover, even short KA(triazole)coumarin showed submicromolar affinity to Cu2+. Only FKA(triazole)coumarin with free amino groups and its shorter analog KA(triazole)coumarin showed strong induced CD spectra upon Cu2+ cation binding. Thus, KA(triazole)coumarin can be considered as the shortest peptidoid sequence with highly sensitive fluorescent and chiral CD response for Cu2+ cation, encouraging further studies with other metal cations. The FKA(triazole) coumarin peptidoids show biorelevant, 10 µM affinity to ds-DNA and ds-RNA, binding within DNA/RNA grooves. Intriguingly, only peptidoid complexes with Cu2+ strongly stabilize ds-DNA and ds-RNA against thermal denaturation, suggesting significant interactions of Cu2+ cation within the DNA/RNA binding site.

COMPARATIVE STUDIES OF THE POTENTIATION OF CORTICOTROPHIN ACTIVITY BY SEVERAL INACTIVE DERIVATIVES

1963 ◽  
Vol 42 (2) ◽  
pp. 209-213 ◽  
Author(s):  
Arthur I. Cohen ◽  
Edward H. Frieden
Keyword(s):  
Biological Activity ◽  
Comparative Studies ◽  
Free Amino ◽  
Hormonal Activity ◽  
Amino Groups

ABSTRACT A number of corticotrophin analogues have been prepared, some of which potentiate the biological activity of the untreated hormone in vitro. The free amino groups of corticotrophin appear to be essential not only for hormonal activity, but also for the interaction of the analogues with the tissue corticotrophin inactivating system which is assumed to account for the potentiating effect.

scholarly journals FREE AMINO GROUPS OF EQUINE γ-GLOBULINS AND A SPECIFIC ANTIBODY

1955 ◽  
Vol 216 (2) ◽  
pp. 621-624
Author(s):  
Mary L. McFadden ◽  
Emil L. Smith
Keyword(s):  
Specific Antibody ◽  
Free Amino ◽  
Amino Groups ◽  
Γ Globulins

scholarly journals FREE AMINO GROUPS AND N-TERMINAL SEQUENCE OF RABBIT ANTIBODIES

1955 ◽  
Vol 214 (1) ◽  
pp. 185-196 ◽  
Author(s):  
Mary L. McFadden ◽  
Emil L. Smith
Keyword(s):  
Free Amino ◽  
Terminal Sequence ◽  
Amino Groups

scholarly journals Monoclonal antibodies identify residues 199–216 of the integrin α2 vWFA domain as a functionally important region within α2β1

2000 ◽  
Vol 350 (2) ◽  
pp. 485-493 ◽  
Author(s):  
Danny S. TUCKWELL ◽  
Lyndsay SMITH ◽  
Michelle KORDA ◽  
Janet A. ASKARI ◽  
Sentot SANTOSO ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Binding Site ◽  
Conformational Changes ◽  
Cation Binding ◽  
Inhibitory Antibody ◽  
Collagen Binding ◽  
Collagen Peptide ◽  
Binding Residue ◽  
Important Region ◽  
Domain Mapping

Integrin α2β1 is the major receptor for collagens in the human body, and the collagen-binding site on the α2 subunit von Willebrand factor A-type domain (vWFA domain) is now well defined. However, the biologically important conformational changes that are associated with collagen binding, and the means by which the vWFA domain is integrated into the whole integrin are not completely understood. We have raised monoclonal antibodies against recombinant α2 vWFA domain for use as probes of function. Three antibodies, JA202, JA215 and JA218, inhibited binding to collagen, collagen I C-propeptide and E-cadherin, demonstrating that their function is important for structurally diverse α2β1 ligands. Cross-blocking studies grouped the epitopes into two clusters: (I) JA202, the inhibitory antibody, Gi9, and a non-inhibitory antibody, JA208; (II) JA215 and JA218. Both clusters were sensitive to events at the collagen binding site, as binding of Gi9, JA202, JA215 and JA218 were inhibited by collagen peptide, JA208 binding was enhanced by collagen peptide, and binding of JA202 was decreased after mutagenesis of the cation-binding residue Thr221 to alanine. Binding of cluster I antibodies was inhibited by the anti-functional anti-β1 antibody Mab13, and binding of Gi9 and JA218 to α2β1 was inhibited by substituting Mn2+ for Mg2+, demonstrating that these antibodies were sensitive to changes initiated outside the vWFA domain. Mapping of epitopes showed that JA202 and Gi9 bound between residues 212–216, while JA208 bound between residues 199–216. We have therefore identified two epitope clusters with novel properties; i.e. they are intimately associated with the collagen-binding site, responsive to conformational changes at the collagen-binding site and sensitive to events initiated outside the vWFA domain.

Mutational and Structural Analysis of the RNA Binding Site for Escherichia coli Ribosomal Protein S7

1994 ◽  
Vol 244 (1) ◽  
pp. 74-85 ◽  
Author(s):  
François Dragon ◽  
Catherine Payant ◽  
Léa Brakier-Gingras
Keyword(s):  
Escherichia Coli ◽  
Structural Analysis ◽  
Ribosomal Protein ◽  
Binding Site ◽  
Rna Binding

scholarly journals The free amino groups of insulin

1945 ◽  
Vol 39 (5) ◽  
pp. 507-515 ◽  
Author(s):  
F. Sanger
Keyword(s):  
Free Amino ◽  
Amino Groups

scholarly journals Experimental and Theoretical Characterization of the High-Affinity Cation-Binding Site of the Purple Membrane

1998 ◽  
Vol 75 (2) ◽  
pp. 777-784 ◽  
Author(s):  
Leonardo Pardo ◽  
Francesc Sepulcre ◽  
Josep Cladera ◽  
Mireia Duñach ◽  
Amílcar Labarta ◽  
...  
Keyword(s):  
Binding Site ◽  
Purple Membrane ◽  
Cation Binding ◽  
High Affinity ◽  
Cation Binding Site ◽  
Theoretical Characterization

scholarly journals Hyperpolarization-activated inward leakage currents caused by deletion or mutation of carboxy-terminal tyrosines of the Na+/K+-ATPase α subunit

2010 ◽  
Vol 135 (2) ◽  
pp. 115-134 ◽  
Author(s):  
Susan Meier ◽  
Neslihan N. Tavraz ◽  
Katharina L. Dürr ◽  
Thomas Friedrich
Keyword(s):  
Binding Site ◽  
Critical Role ◽  
Aromatic Amino Acids ◽  
Cation Binding ◽  
Carboxy Terminus ◽  
Leakage Currents ◽  
Α Subunit ◽  
Inward Currents ◽  
The Common ◽  
Carboxy Terminal

The Na+/K+-ATPase mediates electrogenic transport by exporting three Na+ ions in exchange for two K+ ions across the cell membrane per adenosine triphosphate molecule. The location of two Rb+ ions in the crystal structures of the Na+/K+-ATPase has defined two “common” cation binding sites, I and II, which accommodate Na+ or K+ ions during transport. The configuration of site III is still unknown, but the crystal structure has suggested a critical role of the carboxy-terminal KETYY motif for the formation of this “unique” Na+ binding site. Our two-electrode voltage clamp experiments on Xenopus oocytes show that deletion of two tyrosines at the carboxy terminus of the human Na+/K+-ATPase α2 subunit decreases the affinity for extracellular and intracellular Na+, in agreement with previous biochemical studies. Apparently, the ΔYY deletion changes Na+ affinity at site III but leaves the common sites unaffected, whereas the more extensive ΔKETYY deletion affects the unique site and the common sites as well. In the absence of extracellular K+, the ΔYY construct mediated ouabain-sensitive, hyperpolarization-activated inward currents, which were Na+ dependent and increased with acidification. Furthermore, the voltage dependence of rate constants from transient currents under Na+/Na+ exchange conditions was reversed, and the amounts of charge transported upon voltage pulses from a certain holding potential to hyperpolarizing potentials and back were unequal. These findings are incompatible with a reversible and exclusively extracellular Na+ release/binding mechanism. In analogy to the mechanism proposed for the H+ leak currents of the wild-type Na+/K+-ATPase, we suggest that the ΔYY deletion lowers the energy barrier for the intracellular Na+ occlusion reaction, thus destabilizing the Na+-occluded state and enabling inward leak currents. The leakage currents are prevented by aromatic amino acids at the carboxy terminus. Thus, the carboxy terminus of the Na+/K+-ATPase α subunit represents a structural and functional relay between Na+ binding site III and the intracellular cation occlusion gate.

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