The effect of L-cysteine in different concentrations on the bioleaching of Ni-Cu sulfide was studied with an extremely thermophilic archaea,Acidianus manzaensis. It is found that adding certain amounts of L-cysteine t...The effect of L-cysteine in different concentrations on the bioleaching of Ni-Cu sulfide was studied with an extremely thermophilic archaea,Acidianus manzaensis. It is found that adding certain amounts of L-cysteine to the bioleaching system of Ni-Cu sulfide largely enhances the leaching rate. X-ray diffraction (XRD) patterns show the change of bioleached solid residues and the effect of L-cysteine on the surface charges of minerals. Zeta potential and IR spectra of mineral surface show that the interaction between L-cysteine and mineral leads to the formation of metal complex,which is propitious to the bioleaching of Ni-Cu sulfide by Acidianus manzaensis.展开更多
Previous study on refolding of sulfur oxygenase reductase (SOR) inclusion bodies from recombinant Escherichia coli showed that iron was critical to the activity of the SOR from Acidianus ambivalens. In this study, enz...Previous study on refolding of sulfur oxygenase reductase (SOR) inclusion bodies from recombinant Escherichia coli showed that iron was critical to the activity of the SOR from Acidianus ambivalens. In this study, enzymatic assays showed that 2,2′-Dipyridyl, Tiron and 8-hydroxyquinoline, which are specific for chelating ferrous or ferric ions, strongly inhibited the activity of SOR from A. tengchongensis, suggesting that iron atom is essential for SOR activity. Alignment of several functionally identified SORs and SOR-like sequences from genome database revealed a conserved, putative iron binding motif, H86-X3-H90-Xn-E114-Xn-E129 (numbering according to the Acidianus tengchongensis SOR sequence). Three mutants of SOR were generated by site-directed mutagenesis of H86, H90 and E129 into phenyla-lanine or alanine residue in this study. Circular dichroism spectrum determination indicated that there was no change of the secondary structures of mutant SORs, H86F, H90F and E129A, but all mutants were completely inactive. Through determination of iron contents we found that SOR mutants of H86F, H90F and E129A completely or partially lost iron, while mutants of C31S, C101S, and C104S (generated in a previous study) did not. This result indicated that H86, H90 and E129 but not C31, C101, and C104 were involved in binding to iron atom. Based on this and previous studies, it is proposed that the conserved motifs, C31-Xn-C101-X2-C104 and H86-X3-H90-X23-E114-X14-(E/D)129, are respectively for sulfur and molecular oxygen binding and activation. These two conserved motifs are essential elements for the SOR activity.展开更多
基金Projects(50621063, 30400010) supported by the National Natural Science Foundation of ChinaProject(2010CB630903) supported by the National Basic Research Program of China
文摘The effect of L-cysteine in different concentrations on the bioleaching of Ni-Cu sulfide was studied with an extremely thermophilic archaea,Acidianus manzaensis. It is found that adding certain amounts of L-cysteine to the bioleaching system of Ni-Cu sulfide largely enhances the leaching rate. X-ray diffraction (XRD) patterns show the change of bioleached solid residues and the effect of L-cysteine on the surface charges of minerals. Zeta potential and IR spectra of mineral surface show that the interaction between L-cysteine and mineral leads to the formation of metal complex,which is propitious to the bioleaching of Ni-Cu sulfide by Acidianus manzaensis.
基金Supported by National Natural Science Foundation of China (Grant Nos. 30670018, 30621005)State Key Basic Research and Development Program of China (Grant No. 2004CB719602)
文摘Previous study on refolding of sulfur oxygenase reductase (SOR) inclusion bodies from recombinant Escherichia coli showed that iron was critical to the activity of the SOR from Acidianus ambivalens. In this study, enzymatic assays showed that 2,2′-Dipyridyl, Tiron and 8-hydroxyquinoline, which are specific for chelating ferrous or ferric ions, strongly inhibited the activity of SOR from A. tengchongensis, suggesting that iron atom is essential for SOR activity. Alignment of several functionally identified SORs and SOR-like sequences from genome database revealed a conserved, putative iron binding motif, H86-X3-H90-Xn-E114-Xn-E129 (numbering according to the Acidianus tengchongensis SOR sequence). Three mutants of SOR were generated by site-directed mutagenesis of H86, H90 and E129 into phenyla-lanine or alanine residue in this study. Circular dichroism spectrum determination indicated that there was no change of the secondary structures of mutant SORs, H86F, H90F and E129A, but all mutants were completely inactive. Through determination of iron contents we found that SOR mutants of H86F, H90F and E129A completely or partially lost iron, while mutants of C31S, C101S, and C104S (generated in a previous study) did not. This result indicated that H86, H90 and E129 but not C31, C101, and C104 were involved in binding to iron atom. Based on this and previous studies, it is proposed that the conserved motifs, C31-Xn-C101-X2-C104 and H86-X3-H90-X23-E114-X14-(E/D)129, are respectively for sulfur and molecular oxygen binding and activation. These two conserved motifs are essential elements for the SOR activity.
