科研之友
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摘要
A unique protein, bioremediase (UniProt Knowledgebase Accession No.: P86277), isolated from a hot spring bacterium BKH1 (GenBank Accession No.: FJ177512), has shown to exhibit silica leaching activity when incorporated to prepare bio-concrete material. Matrix-assisted laser desorption ionization mass spectrometry analysis suggests that bioremediase is 78 % homologous to bovine carbonic anhydrase II though it does not exhibit carbonic anhydrase-like activity. Bioinformatics study is performed for understanding the various physical and chemical parameters of the protein which predicts the involvement of zinc encircled by three histidine residues (His94, His96 and His119) at the active site of the protein. Isothermal titration calorimetric-based thermodynamic study on diethyl pyrocarbonate-modified protein recognizes the presence of Zn2+ in the enzyme moiety. Exothermic to endothermic transition as observed during titration of the protein with Zn2+ discloses that there are at least two binding sites for zinc within the protein moiety. Addition of Zn2+ regains the activity of EDTA chelated bioremediase confirming the presence of extra binding site of Zn2+ in the protein moiety. Revival of folding pattern of completely unfolded urea-treated protein by Zn2+ explains the participatory role of zinc in structural stability of the protein. Restoration of the lambda (max) in intrinsic fluorescence emission study of the urea-treated protein by Zn2+ similarly confirms the involvement of Zn in the refolding of the protein. The utility of bioremediase for silica nanoparticles preparation is observed by field emission scanning electron microscopy. [GRAPHICS] .
- 出版日期2015-7
