Hemopexin reverses activation of lung eIF2α and decreases mitochondrial injury in chlorine-exposed mice.

We assessed the mechanisms by which nonencapsulated heme, released in the plasma of mice after exposure to chlorine (Cl2) gas, resulted in the initiation and propagation of acute lung injury. We exposed adult male and female C57BL/6 mice to Cl2 (500 ppm for 30 min), returned them to room air, and injected them intramuscularly with either human hemopexin (hHPX; 5 µg/g BW in 50-µL saline) or vehicle at 1 h post-exposure. Upon return to room air, Cl2-exposed mice, injected with vehicle, developed respiratory acidosis, increased concentrations of plasma proteins in the alveolar space, lung mitochondrial DNA injury, increased levels of free plasma heme, and major alterations of their lung proteome. hHPX injection mice mitigated the onset and development of lung and mitochondrial injury and the increase of plasma heme, reversed the Cl2-induced changes in 83 of 237 proteins in the lung proteome at 24 h post-exposure, and improved survival at 15 days post-exposure. Systems biology analysis of the lung global proteomics data showed that hHPX reversed changes in a number of key pathways including elF2 signaling, verified by Western blotting measurements. Recombinant human hemopexin, generated in tobacco plants, injected at 1 h post-Cl2 exposure, was equally effective in reversing acute lung and mtDNA injury. The results of this study offer new insights as to the mechanisms by which exposure to Cl2 results in acute lung injury and the therapeutic effects of hemopexin.NEW & NOTEWORTHY Herein, we demonstrate that exposure of mice to chlorine gas causes significant changes in the lung proteome 24 h post-exposure. Systems biology analysis of the proteomic data is consistent with damage to mitochondria and activation of eIF2, the master regulator of transcription and protein translation. Post-exposure injection of hemopexin, which scavenges free heme, attenuated mtDNA injury, eIF2α phosphorylation, decreased lung injury, and increased survival.

Hemopexin Reverses Activation of Lung eIF2a and Decreases Mitochondrial Injury in Chlorine Exposed Mice.

We assessed the mechanisms by which non-encapsulated heme, released in the plasma of mice post exposure to chlorine (Cl 2 ) gas, resulted in the initiation and propagation of acute lung injury. We exposed adult C57BL/6 male and female to Cl 2 (500 ppm for 30 min) in environmental chambers and returned them to room air and injected them intramuscularly with a single dose of human hemopexin (hHPX; 5 µg/ g BW), the most efficient scavenger of heme, 30-60 min post exposure. Concentrations of hHPX in plasma of air and Cl 2 exposed mice were 9081±900 vs. 1879± 293 at 6 h and 2966±463 vs. 1555±250 at 50 h post injection (ng/ml; X±1 SEM=3; p<0.01). Cl 2 exposed mice developed progressive acute lung injury post exposure characterized by increased concentrations of plasma heme, marked inflammatory response, respiratory acidosis and increased concentrations of plasma proteins in the alveolar space. Injection of hHPX decreased the onset of acute lung injury at 24 h post exposure; mean survival, for the saline and hHPX groups were 40 vs. 80% (P<0.001) at 15 d post exposure. Non-supervised global proteomics analysis of mouse lungs at 24 h post exposure, revealed the upregulation of 92 and downregulation of 145 lung proteins. Injection of hHPX at one h post exposure moderated the Cl 2 induced changes in eighty-three of these 237 lung proteins. System biology analysis of the global proteomics data showed that hHPX reversed changes in mitochondrial dysfunction and elF2 and integrin signaling. Western blot analysis of lung tissue showed significant increase of phosphorylated elF2 at 24 h post exposure in vehicle treated mice but normal levels in those injected with hHPX. Similarly, RT-PCR analysis of lung tissue showed that hHPX reversed the onset of mtDNA lesions. A form of recombinant human hemopexin generated in tobacco plants was equally effective in reversing acute lung and mtDNA injury. The results of this study offer new insights as to the mechanisms by which exposure to Cl 2 results in acute lung injury and to the therapeutic effects of hemopexin.

Isolation of sophorose during sophorolipid production and studies of its stability in aqueous alkali: epimerisation of sophorose to 2-O-ß-D-glucopyranosyl-D-mannose.

NMR and anion exchange chromatography analysis of the waste streams generated during the commercial production of sophorolipids by the yeast Candida bombicola identified the presence of small but significant quantities (1% w/v) of free sophorose. Sophorose, a valuable disaccharide, was isolated from the aqueous wastes using a simple extraction procedure and was purified by chromatography on a carbon celite column providing easy access to large quantities of the disaccharide. Experiments were undertaken to identify the origin of sophorose and it is likely that acetylated sophorose derivatives were produced by an enzyme catalysed hydrolysis of the glucosyl-lipid bond of sophorolipids; the acetylated sophorose derivatives then undergo hydrolysis to release the parent disaccharide. Treatment of sophorose with aqueous alkali at elevated temperatures (0.1M NaOH at 50 °C) resulted in C2-epimerisation of the terminal reducing sugar and its conversion to the corresponding 2-O-ß-D-glucopyranosyl-D-mannose which was isolated and characterised. In aqueous alkaline solution ß-(1,2)-linked glycosidic bonds do not undergo either hydrolysis or peeling reactions.

Purification and characterization of recombinant Streptomyces griseus aminopeptidase.

Recombinant Streptomyces griseus aminopeptidase (SGAP) was produced using Cangene's expression system, CANGENUS. This heat-stable aminopeptidase with an N-terminal Ala-Pro-Asp-Ile-Pro-Leu-Ala-Asn-Val-Lys-Ala sequence was purified from 16L of Streptomyces lividans fermentation supernatant with high purity and 19.5% recovery rate. This was achieved by the combination of hydrophobic-interaction and size-exclusion chromatographic procedures. The calcium-activated zinc metalloprotein demonstrated no loss of activity at -20 degrees C for at least 8 weeks in both liquid and freeze-dried formulations. The recombinant SGAP showed an apparent molecular mass of 31 kDa by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and 26.8 kDa by gel filtration. The simple, high-yield, inexpensive purification method with few intermediate steps provides a novel and practical procedure for large-scale production of active recombinant S. griseus aminopeptidase.