In the absence of thioredoxins, what are the reductants for peroxiredoxins in Thermotoga maritima?

Three peroxiredoxins (Prxs) were identified in Thermotoga maritima, which possesses neither glutathione nor typical thioredoxins: one of the Prx6 class; one 2-Cys PrxBCP; and a unique hybrid protein containing an N-terminal 1-Cys PrxBCP domain fused to a flavin mononucleotide-containing nitroreductase (Ntr) domain. No peroxidase activity was detected for Prx6, whereas both bacterioferritin comigratory proteins (BCPs) were regenerated by a NADH/thioredoxin reductase/glutaredoxin (Grx)-like system, constituting a unique peroxide removal system. Only two of the three Grx-like proteins were able to support peroxidase activity. The inability of TmGrx1 to regenerate oxidized 2-Cys PrxBCP probably results from the thermodynamically unfavorable difference in their disulfide/dithiol E(m) values, -150 and -315 mV, respectively. Mutagenesis of the Prx-Ntr fusion, combined with kinetic and structural analyses, indicated that electrons are not transferred between its two domains. However, their separate activities could function in a complementary manner, with peroxide originating from the chromate reductase activity of the Ntr domain reduced by the Prx domain.

{2-[(2-Acetyl-hydrazin-1-yl-idene)methyl-κN,O]-6-methoxy-phenolato-κO}(nitrato-κO)copper(II) monohydrate.

In the title complex, [Cu(C(10)H(11)N(2)O(3))(NO(3))]·H(2)O, prepared from the Schiff base N'-(3-meth-oxy-2-oxidobenzyl-idene)-acetohydrazide, the Cu(II) atom is coordinated by two O atoms and one N atom from the ligand and one O atom from a nitrate group in a distorted square-planar geometry. The Cu(II) atom has a weak inter-action with another O atom of the nitrate group. The two O atoms of the tridentate Schiff base ligand are in a trans arrangement. O-H⋯O and N-H⋯O hydrogen bonds involving the uncoordinated water mol-ecule are observed.

Recombinant plant gamma carbonic anhydrase homotrimers bind inorganic carbon.

Gamma carbonic anhydrases (gammaCA) are widespread in Prokaryotes. In Eukaryotes, homologous genes were found only in plant genomes. In Arabidopsis and maize, the corresponding gene products are subunits of mitochondrial Complex I. At present, only gammaCA homotrimers of Methanosarcina thermophila (CAM) show reversible carbon dioxide (CO(2)) hydration activity. In the present work, it is shown that recombinant plant gammaCA2 could form homotrimers and bind H(14)CO(3)(-). However, they are unable to catalyse the reversible hydration of CO(2). These results suggest that plant gammaCAs do not act as carbonic anhydrases but with a related activity possibly contributing to recycle CO(2) in the context of photorespiration.

Bis(benzohydrazide-κO,N')bis-(nitrato-κO)copper(II).

In the title compound, [Cu(NO(3))(2)(C(7)H(8)N(2)O)(2)], the Cu(II) atom is located on a centre of inversion, and is coordinated by two bidentate benzohydrazide ligands and two monodentate nitrate anions in an axially distorted octa-hedral geometry within an N(2)O(4) donor set. The crystal structure is stabilized by N-H⋯O and weak N-H⋯N hydrogen bonds.

Overproduction, purification, crystallization and preliminary X-ray analysis of the peroxiredoxin domain of a larger natural hybrid protein from Thermotoga maritima.

Thermotoga maritima contains a natural hybrid protein constituted of two moieties: a peroxiredoxin domain at the N-terminus and a nitroreductase domain at the C-terminus. The peroxiredoxin (Prx) domain has been overproduced and purified from Escherichia coli cells. The recombinant Prx domain, which is homologous to bacterial Prx BCP and plant Prx Q, folds properly into a stable protein that possesses biological activity. The recombinant protein was crystallized and synchrotron data were collected to 2.9 A resolution. The crystals belonged to the tetragonal space group I422, with unit-cell parameters a = b = 176.67, c = 141.20 A.

Structure-function analysis of the antiangiogenic ATWLPPR peptide inhibiting VEGF(165) binding to neuropilin-1 and molecular dynamics simulations of the ATWLPPR/neuropilin-1 complex.

Heptapeptide ATWLPPR (A7R), identified in our laboratory by screening a mutated phage library, was shown to bind specifically to neuropilin-1 (NRP-1) and then to selectively inhibit VEGF(165) binding to this receptor. In vivo, treatment with A7R resulted in decreasing breast cancer angiogenesis and growth. The present work is focused on structural characterization of A7R. Analogs of the peptide, obtained by substitution of each amino acid with alanine (alanine-scanning) or by amino acid deletion, have been systematically assayed to determine the relative importance of the side chains of each residue with respect to the inhibitory effect of A7R on VEGF(165) binding to NRP-1. We show here the importance of the C-terminal sequence LPPR and particularly the key role of C-terminal arginine. In solution, A7R displays significant secondary structure of the backbone adopting an extended conformation. However, the functional groups of arginine are very flexible in the absence of NRP-1 pointing to an induced fit upon binding to the receptor. A MD trajectory of the A7R/NRP-1 complex in explicit water, based on the recent tuftsin/NRP-1 crystal structure, has revealed the hydrogen-bonding network that contributes to A7R's binding activity.

Helical aquatubes of calix[4]arene di-methoxycarboxylic acid.

Two trimeric units of calix[4]arene di-methoxycarboxylic acid form a six-pointed star architecture that, in turn, generates triple helical aquatubes which intermesh between themselves by aromatic-aromatic interdigitation of the macrocycle.

A new packing motif for para-sulfonatocalix[4]arene: the solid state structure of the para-sulfonatocalix[4]arene D-arginine complex.

The solid-state structure of the complex of para-sulfonatocalix[4]arene with d-arginine, contains a water channel diagonal to a zigzag bilayer of the host, within the bilayer six crystallographically independent molecules of arginine are present, four being included in the calix cavities.

Solid-state caging of 1,10-phenanthroline pi-pi stacked dimers by calix[4]arene dihydroxyphosphonic acid.

The calix[4]arene dihydroxyphosphonic acid-1,10-phenanthroline complex shows caging of the guest molecules as a pi-pi stacked dimer in a cavity formed by intermolecular hydrogen bonds and aromatic walls formed by the calixarene.

The structure of a self-assembled calixarene aqua-channel system.

The crystal structure of the complex 12.calix-[4]-arene dihydroxyphosphonic acid, 12.propane diammonium, 12.ethanol and 40.water molecules is based on dimeric units of the calix, assembled via trigonal units into a hexameric tube of 15 A radius and 16 A depth, further assemby via spanning propane diammonium cations and ethanol molecules forms a channel (40 A), selectively containing all the water molecules.

[Hydroxy(aryl)methylene]diphosphonic acids, a class of drugs in bone pathology treatments, crystallize as head-to-head dimers.

Two [hydroxy(aryl)methylene]diphosphonic acids have been crystallized as dimers. The first compound, [hydroxy(phenyl)methylene]diphosphonic acid monohydrate, C(7)H(10)O(7)P(2).H(2)O, crystallizes in the non-centrosymmetric space group P2(1), with the two enantiomers related by a non-crystallographic centre of inversion, while the second compound, [hydroxy(4-nitrophenyl)methylene]diphosphonic acid tetrahydrofuran disolvate, C(7)H(9)NO(9)P(2).2C(4)H(8)O, crystallizes in the centrosymmetric space group P2(1)/c and uses the centre of symmetry to form the same dimer.