Crystal structure of sulfonic peroxiredoxin Ahp1 in complex with thioredoxin Trx2 mimics a conformational intermediate during the catalytic cycle.

Peroxiredoxin (Prx) is a thiol-based peroxidase that eliminates reactive oxygen species to avoid oxidative damage. Alkyl hydroperoxide reductase Ahp1 is a novel and specific typical 2-cysteine Prx. Here, we present the crystal structure of sulfonic Ahp1 complexed with thioredoxin Trx2 at 2.

New structural insights into the recognition of undamaged splayed-arm DNA with a single pair of non-complementary nucleotides by human nucleotide excision repair protein XPA.

XPA (Xeroderma pigmentosum complementation group A) is a core scaffold protein that plays significant roles in DNA damage verification and recruiting downstream endonucleases in the nucleotide excision repair (NER) pathway. Here, we present the 2.81 Å resolution crystal structure of the DNA-binding domain (DBD) of human XPA in complex with an undamaged splayed-arm DNA substrate with a single pair of non-complementary nucleotides.

Structural characterization of the redefined DNA-binding domain of human XPA.

XPA (xeroderma pigmentosum complementation group A), a key scaffold protein in nucleotide excision repair (NER) pathway, is important in DNA damage verification and repair proteins recruitment. Earlier studies had mapped the minimal DNA-binding domain (MBD) of XPA to a region corresponding to residues 98-219. However, recent studies indicated that the region involving residues 98-239 is the redefined DNA-binding domain (DBD), which binds to DNA substrates with a much higher binding affinity than MBD and possesses a nearly identical binding affinity to the full-length XPA protein.

The redefined DNA-binding domain of human xeroderma pigmentosum complementation group A: production, crystallization and structure solution.

Human xeroderma pigmentosum complementation group A (XPA) is a scaffold protein that plays significant roles in DNA-damage verification and in recruiting downstream endonucleases to facilitate the repair of DNA lesions in nucleotide-excision repair. XPA (residues 98-219) has been identified as a DNA-binding domain and has been extensively studied in the last two decades. However, the most recent studies have redefined the DNA-binding domain as XPA (residues 98-239); it exerts a remarkably higher DNA-binding affinity than XPA and has a binding affinity that is quite similar to that of the full-length protein.

Crystal structure and SUMO binding of Slx1-Slx4 complex.

The SLX1-SLX4 complex is a structure-specific endonuclease that cleaves branched DNA structures and plays significant roles in DNA recombination and repair in eukaryotic cells. The heterodimeric interaction between SLX1 and SLX4 is essential for the endonuclease activity of SLX1. Here, we present the crystal structure of Slx1 C-terminal zinc finger domain in complex with the C-terminal helix-turn-helix domain of Slx4 from Schizosaccharomyces pombe at 2.

The N-terminal β-sheet of peroxiredoxin 4 in the large yellow croaker Pseudosciaena crocea is involved in its biological functions.

Peroxiredoxins (Prxs) are thiol-specific antioxidant proteins that exhibit peroxidase and peroxynitrite reductase activities involved in the reduction of reactive oxygen species. The peroxiredoxin Prx4 from the large yellow croaker Pseudosciaena crocea is a typical 2-Cys Prx with an N-terminal signal peptide. We solved the crystal structure of Prx4 at 1.

Structural snapshots of yeast alkyl hydroperoxide reductase Ahp1 peroxiredoxin reveal a novel two-cysteine mechanism of electron transfer to eliminate reactive oxygen species.

Peroxiredoxins (Prxs) are thiol-specific antioxidant proteins that protect cells against reactive oxygen species and are involved in cellular signaling pathways. Alkyl hydroperoxide reductase Ahp1 belongs to the Prx5 subfamily and is a two-cysteine (2-Cys) Prx that forms an intermolecular disulfide bond. Enzymatic assays and bioinformatics enabled us to re-assign the peroxidatic cysteine (C(P)) to Cys-62 and the resolving cysteine (C(R)) to Cys-31 but not the previously reported Cys-120.

Crystal structures and putative interface of Saccharomyces cerevisiae mitochondrial matrix proteins Mmf1 and Mam33.

The yeast Saccharomyces cerevisiae mitochondrial matrix factor Mmf1, a member in the YER057c/Yigf/Uk114 family, participates in isoleucine biosynthesis and mitochondria maintenance. Mmf1 physically interacts with another mitochondrial matrix protein Mam33, which is involved in the sorting of cytochrome b₂ to the intermembrane space as well as mitochondrial ribosomal protein synthesis. To elucidate the structural basis for their interaction, we determined the crystal structures of Mmf1 and Mam33 at 1.

Structural insights into the substrate tunnel of Saccharomyces cerevisiae carbonic anhydrase Nce103.

Background: The carbonic anhydrases (CAs) are involved in inorganic carbon utilization. They have been classified into six evolutionary and structural families: alpha-, beta-, gamma-, delta-, epsilon-, zeta- CAs, with beta-CAs present in higher plants, algae and prokaryotes. The yeast Saccharomyces cerevisiae encodes a single copy of beta-CA Nce103/YNL036W.

[Research of FTIR and XRD study on the organic modification of bentonites].

Organobentonites were prepared to improve the compatibility between bentonites and organic phase. The change of lamellar structure after organic modification was observed. Na+ -bentonites and octadecylamine were used to exchange the Na+ which is in the layers of bentonites, and the organobentonites were obtained.

[Surface grafting modification and stabilization of Kevlar fiber].

Chemical disposal was used to bring the activity group onto the surface of Kevlar fiber for the purpose of surface grafting modification. The interfacial constitution of the grafting of toluene-2,4-diisocyanate (TDI) onto Kevlar fiber was determined by Fourier transform infrared spectroscopy. In the mean time, hexyl-lactam stabilization and poly-glycol (400, PEG) stabilization on the grafted product were also studied.

[Study on the modification of short chain phoshate ammonium salt of bentonites].

The Organobentonites were synthesized by means of the ionexchange reaction of Na+ between tetramethylammonium chloride and tetrabutylammonium chloride quaternary ammonium salts, and sodium base bentonites. The authors used FTIR, X-ray diffraction diagram and DSC thermograms to characterize the structure of the modified bentonites, and discussed the effect of different quaternary ammonium salt on the properties of organobentonites. The results showed that ions of the surfactants had entered into the chip layer of the bentonites, changed the hydrophilic environment of the chip layer into a hydrophobic environment, increased the distance among the chip layers, and improved the compatibility between montmorillonite andthe organic phases.

[Research on the modification of Kevlar fiber by polypropylene glycol and cis-2-butene-1,4-diol].

The mechanism of the modification of Kevlar fiber by polypropylene glycol(PPG) and cis-2-butene-1, 4-diol was studied in the paper, the authors learned the esterification of toluene-2, 4-diisocyanate (TDI) onto Kevlar fiber by infrared spectrum. In the mean time, the infrared spectrograms of the productions which steadily disposed by PPG and butendiol were analysed respectively, the result showed that the intensity of the bands was reinforced at about 1700-1720 cm(-1) after the samples were steadily disposed, that is to say, the group of --NCO has been stabilized into --NHCO group, the effect of steady disposal was obvious; but the disposal effect of butendiol was apparently better than PPG's at the same condition. Finally, the authors compared the influence of different mol rates between TDI and butendiol on the productions.

[Preparation and properties of organobentonites].

The chemistry organobentonites were synthesized by means of the ionexchange reaction between single-octadecyl trimethyl ammonium chloride(SOAC), di-octadecyl dimethyl ammonium chloride (DOAC) , tri-octadecyl methylammonium chloride (TOAC) quaternary ammonium salts and sodium base bentonies, respectively. The authors used FTIR, X-ray diffraction diagram and DSC thermograms to characterate the structure of the modified bentonites, and discussed the effect of different quaternary ammonium salt on the properties of organobentonites. The results showed that ion of the surfactants had entered into the chip layer of the bentonites, and changed the hydrophilic environment of the chip layer into hydrophobic environment and increased the distance among the chip layer, all of these had laid a base for the preparation of the nanometer composite material of high polymer/bentonite.

[Structural characterization of rare-earth stearate and its thermal stability mechanism for PVC].

Structural characterization of rare-earth stearate was conducted by FTIR and XRD. The results show that the bonds between the stearate and rare-earth metal ions in rare-earth stearate are main ionic character and have the stratified crystalline structure with the crystal layer formed from a plane layer of rare-earth ions combined with two layers of fully extended zigzag chains of stearic acid radicals arranged parallell to each other on its both sides, and the rare-earth ions axes are inclined to the crystal layer planes in it. Congo red test showed that the stabilizing time increased when the stabilizers' concentration increased.

[The research on the surfacial modification of organic high-performance Kevlar fiber].

In the paper the authors tried to use chemical disposal to bring the activity mass onto the surface of Kevlar fiber with the purpose of surface graft modification. In the paper the authors used the FTIR spectra to discuss the graft of toluene-2, 4-diisocyanate onto Kevlar fiber. The authors studied and analysed the effect of hydrolytic time on the content of -O-H group of the production, and the effect of hydrolyzation and hexyl-lactam steadily disposing on the graft reaction.