scholarly journals Four cytotoxic N4-substituted thiosemicarbazones derived from 2-hydroxynaphthalene-1-carboxaldehyde

2003 ◽  
Vol 59 (11) ◽  
pp. o629-o633 ◽  
Author(s):  
Paul V. Bernhardt ◽  
Lorraine M. Caldwell ◽  
David B. Lovejoy ◽  
Des R. Richardson
Keyword(s):  
Dimethyl Sulfoxide ◽  
Crystal Structures ◽  
Metal Ion ◽  
Antitumour Activity ◽  
Donor Ligands ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
X Ray ◽  
Conformational Variations ◽  
Optimum Conformation

The X-ray crystal structures are reported of four novel and potentially O,N,S-tridentate donor ligands that demonstrate antitumour activity. These ligands are 1-[(4-methylthiosemicarbazono)methyl]-2-naphthol, C13H13N3OS, (III), 1-[(4-ethylthiosemicarbazono)methyl]-2-naphthol, C14H15N3OS, (IV), 1-[(4-phenylthiosemicarbazono)methyl]-2-naphthol, C18H15N3OS, (V), and 1-[(4,4-dimethylthiosemicarbazono)methyl]-2-naphthol dimethyl sulfoxide solvate, C14H15N3OS·C2H6OS, (VI). These chelators are N4-substituted thiosemicarbazones, each based on the same parent aldehyde, namely 2-zhydroxynaphthalene-1-carboxaldehyde isonicotinoylhydrazone. Conformational variations within this series are discussed in relation to the optimum conformation for metal-ion binding.

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.

Effects of Oxidation State on Metal Ion Binding byMedicago sativa(Alfalfa):  Atomic and X-ray Absorption Spectroscopic Studies with Fe(II) and Fe(III)

2000 ◽  
Vol 34 (4) ◽  
pp. 693-698 ◽  
Author(s):  
K. J. Tiemann ◽  
J. L. Gardea-Torresdey ◽  
G. Gamez ◽  
K. Dokken ◽  
Irene Cano-Aguilera ◽  
...  
Keyword(s):  
Oxidation State ◽  
Metal Ion ◽  
Spectroscopic Studies ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
X Ray ◽  
X Ray Absorption

Metal Ion Binding to Calixarenes: Pendent Arm Coordination Assisted by Self-Inclusion

1994 ◽  
Vol 47 (6) ◽  
pp. 1185 ◽  
Author(s):  
JM Harrowfield ◽  
M Mocerino ◽  
BW Skelton ◽  
CR Whitaker ◽  
AH White
Keyword(s):  
Structural Characterization ◽  
Metal Ion ◽  
Room Temperature ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Cone Conformation ◽  
X Ray ◽  
Partial Cone ◽  
Arm Coordination

The synthesis and room-temperature single-crystal X-ray structural characterization of 25,27- di(allyloxy)-5,17-di-t-butyl-26,28-dimethoxycalix[4]arene are recorded. Crystals are monoclinic, C2/c, a 29.089(5), b 10.742(2), c 26.218(8) Ǻ, β 110.09(2)°, Z = 8; the structure was refined to a residual of 0.065 for 4103 independent 'observed' [I > 3σ(I)] reflections. The flattened partial cone conformation of the molecule allows inclusion of one of the methoxy substituents in a way which could block inclusion of a metal ion capable of polyhapto aromatic coordination and which may therefore explain why solution n.m.r. measurements indicate that silver(I) binds to the pendent alkene groups.

scholarly journals X-ray Crystallographic Studies of Substrate Binding to Aristolochene Synthase Suggest a Metal Ion Binding Sequence for Catalysis

2008 ◽  
Vol 283 (22) ◽  
pp. 15431-15439 ◽  
Author(s):  
Ekaterina Y. Shishova ◽  
Fanglei Yu ◽  
David J. Miller ◽  
Juan A. Faraldos ◽  
Yuxin Zhao ◽  
...  
Keyword(s):  
Metal Ion ◽  
Substrate Binding ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
X Ray ◽  
Aristolochene Synthase ◽  
Binding Sequence
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