Conformational Change Induced by Metal-Ion-Binding to DNA Containing the Artificial 1,2,4-Triazole Nucleoside

2007 ◽  
Vol 46 (24) ◽  
pp. 10114-10119 ◽  
Author(s):  
Dominik Böhme ◽  
Nicole Düpre ◽  
Dominik A. Megger ◽  
Jens Müller
Keyword(s):  
Conformational Change ◽  
Metal Ion ◽  
Ion Binding ◽  
Metal Ion Binding

scholarly journals Isolation, characterization and metal-ion-binding properties of the α-subunit from S-100a protein

1986 ◽  
Vol 237 (3) ◽  
pp. 757-764 ◽  
Author(s):  
I K M Leung ◽  
R S Mani ◽  
C M Kay
Keyword(s):  
Conformational Change ◽  
Metal Ion ◽  
Polyacrylamide Gel ◽  
Alpha Subunit ◽  
Ion Binding ◽  
Difference Spectroscopy ◽  
Metal Ion Binding ◽  
Emission Maximum ◽  
Fluorescence Measurements ◽  
Fluorescence Titration

The brain-specific S-100 protein is a mixture of two predominant components, S-100a and S-100b, with subunit compositions of alpha beta and beta beta respectively. In the present study, the alpha-subunit, isolated from S-100a by using anion-exchange chromatography in the presence of 8 M-urea, was homogeneous by the criteria of SDS/polyacrylamide-gel, urea/SDS/polyacrylamide-gel and non-SDS/polyacrylamide-gel electrophoresis. The alpha-subunit underwent a conformational change upon binding Ca2+ and Zn2+ at pH 7.5, as revealed by u.v. difference spectroscopy, c.d. and fluorescence measurements. Far-u.v. c.d. studies indicated the apparent alpha-helical content to fall when the protein bound either Ca2+ or Zn2+. Addition of Ca2+ to the alpha-subunit resulted in exposing to the solvent the single tryptophan residue and one or more tyrosine and phenylalanine residues. Zn2+ induced only a small conformational change, and among the aromatic chromophores only tyrosine residues were affected to a small extent. Ca2+ was able to bind to the alpha-subunit in the presence of Zn2+, and the two metal-ion-binding sites appeared to be different. When the apoprotein was excited at 280 nm, the fluorescence emission maximum was located at 337 nm. In the presence of Ca2+, the emission maximum occurred at 340 nm and was accompanied by a nearly 25% increase in fluorescence intensity. Fluorescence titration with Ca2+ at pH 7.5 revealed only one class of binding site, with a Kd value of 1.26 × 10(-4) M. The effect of K+ on the protein was slightly antagonistic to that of Ca2+, as indicated by u.v. difference spectroscopy and fluorescence titration.

scholarly journals High Affinity Agonistic Metal Ion Binding Sites within the Melanocortin 4 Receptor Illustrate Conformational Change of Transmembrane Region 3

2003 ◽  
Vol 278 (51) ◽  
pp. 51521-51526 ◽  
Author(s):  
Malin C. Lagerström ◽  
Janis Klovins ◽  
Robert Fredriksson ◽  
Davids Fridmanis ◽  
Tatjana Haitina ◽  
...  
Keyword(s):  
Conformational Change ◽  
Binding Sites ◽  
Metal Ion ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Transmembrane Region ◽  
High Affinity ◽  
Melanocortin 4 Receptor ◽  
Ion Binding Sites ◽  
Metal Ion Binding Sites

Photophysical Characterisation, Metal Ion Binding and Enantiomeric Recognition of Chiral Ligands Containing Phenazine Fluorophore

2004 ◽  
Vol 69 (4) ◽  
pp. 885-896 ◽  
Author(s):  
Luisa Stella Dolci ◽  
Péter Huszthy ◽  
Erika Samu ◽  
Marco Montalti ◽  
Luca Prodi ◽  
...  
Keyword(s):  
Metal Ion ◽  
Photophysical Properties ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Ammonium Ions ◽  
Enantiomerically Pure ◽  
Binding Process ◽  
High Affinity ◽  
Enantiomeric Recognition ◽  
Chiral Species

Enantiomerically pure dimethyl- and diisobutyl-substituted phenazino-18-crown-6 ligands bind metal and ammonium ions and also primary aralkylammonium perchlorates in acetonitrile with high affinity, causing pronounced changes in their luminescence properties. In addition, they show enantioselectivity towards chiral primary aralkylammonium perchlorates. The possibility to monitor the binding process by photoluminescence spectroscopy can gain ground for the design of very efficient enantioselective chemosensors for chiral species. The observed changes in the photophysical properties are also an important tool for understanding the interactions present in the adduct.

scholarly journals Snapshots of a Non-Canonical RdRP in Action

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1260
Author(s):  
Diego S. Ferrero ◽  
Michela Falqui ◽  
Nuria Verdaguer
Keyword(s):  
Metal Ion ◽  
Rna Viruses ◽  
Ion Binding ◽  
Genome Replication ◽  
Metal Ion Binding ◽  
Insect Virus ◽  
X Ray ◽  
Template Strand ◽  
Nucleotide Incorporation ◽  
Elongation Process

RNA viruses typically encode their own RNA-dependent RNA polymerase (RdRP) to ensure genome replication and transcription. The closed “right hand” architecture of RdRPs encircles seven conserved structural motifs (A to G) that regulate the polymerization activity. The four palm motifs, arranged in the sequential order A to D, are common to all known template dependent polynucleotide polymerases, with motifs A and C containing the catalytic aspartic acid residues. Exceptions to this design have been reported in members of the Permutotetraviridae and Birnaviridae families of positive single stranded (+ss) and double-stranded (ds) RNA viruses, respectively. In these enzymes, motif C is located upstream of motif A, displaying a permuted C–A–B–D connectivity. Here we study the details of the replication elongation process in the non-canonical RdRP of the Thosea asigna virus (TaV), an insect virus from the Permutatetraviridae family. We report the X-ray structures of three replicative complexes of the TaV polymerase obtained with an RNA template-primer in the absence and in the presence of incoming rNTPs. The structures captured different replication events and allowed to define the critical interactions involved in: (i) the positioning of the acceptor base of the template strand, (ii) the positioning of the 3’-OH group of the primer nucleotide during RNA replication and (iii) the recognition and positioning of the incoming nucleotide. Structural comparisons unveiled a closure of the active site on the RNA template-primer binding, before rNTP entry. This conformational rearrangement that also includes the repositioning of the motif A aspartate for the catalytic reaction to take place is maintained on rNTP and metal ion binding and after nucleotide incorporation, before translocation.

Sign in / Sign up

Export Citation Format

Share Document