A further insight into the biosorption mechanism of Au(III) by infrared spectrometry

BMC Biotechnology

Research Article

Miao Wang¹  Qiaoling Li¹  Zhenling Xu²  Zhongyu Lin²  Yiwen Ye² 

[1] Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, PR China;State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, PR China;

关键词: Biomass;    Biosorption;    Peptide Bond;    Protein Secondary Structure;    Carboxylate Anion;   

DOI  :  10.1186/1472-6750-11-98

 received in 2010-05-31, accepted in 2011-10-27,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundThe interactions of microbes with metal ions form an important basis for our study of biotechnological applications. Despite the recent progress in studying some properties of Au(III) adsorption and reduction by Bacillus megatherium D01 biomass, there is still a need for additional data on the molecular mechanisms of biosorbents responsible for their interactions with Au(III) to have a further insight and to make a better exposition.ResultsThe biosorption mechanism of Au(III) onto the resting cell of Bacillus megatherium D01 biomass on a molecular level has been further studied here. The infrared (IR) spectroscopy on D01 biomass and that binding Au(III) demonstrates that the molecular recognition of and binding to Au(III) appear to occur mostly with oxygenous- and nitrogenous-active groups of polysaccharides and proteins in cell wall biopolymers, such as hydroxyl of saccharides, carboxylate anion of amino-acid residues (side-chains of polypeptide backbone), peptide bond (amide I and amide II bands), etc.; and that the active groups must serve as nucleation sites for Au(0) nuclei growth. A further investigation on the interactions of each of the soluble hydrolysates of D01, Bacillus licheniformis R08, Lactobacillus sp. strain A09 and waste Saccharomyces cerevisiae biomasses with Au(III) by IR spectrometry clearly reveals an essential biomacromolecule-characteristic that seems the binding of Au(III) to the oxygen of the peptide bond has caused a significant, molecular conformation-rearrangement in polypeptide backbones from β-pleated sheet to α-helices and/or β-turns of protein secondary structure; and that this changing appears to be accompanied by the occurrence, in the peptide bond, of much unbound -C=O and H-N- groups, being freed from the inter-molecular hydrogen-bonding of the β-pleated sheet and carried on the helical forms, as well as by the alternation in side chain steric positions of protein primary structure. This might be reasonably expected to result in higher-affinity interactions of peptide bond and side chains with Au(III).ConclusionsThe evidence suggests that the polypeptides appear to be activated by the intervention of Au(III) via the molecular reconformation and in turn react upon Au(III) actively and exert profound impacts on the course of Au(0) nucleation and crystal growth.

【 授权许可】

CC BY   
© Lin et al; licensee BioMed Central Ltd. 2011