Correlating metal ionic characteristics with biosorption capacity of an yeast using QSAR model based on classifications of metal ions
利用QSAR模型探讨分类条件下金属离子性质与酵母吸附容量之间的关系

Based on classification of metal ions (hard or soft ions), the relationship between metal ionic characteristics and the biosorption capacity of ions was established using QSAR model. The maximum biosorption capacity (qmax) of Pb2+, Ag+, Cr3+, Cu2+, Zn2+, Cd2+, Co2+, Sr2+, Ni2+ or Cs+ by the waste biomass of Saccharomyces cerevisiae, determined by the Langmuir isotherm model, was set as activity parameter, and twenty two physiochemical characteristics of metal ions were set as structure parameters in setting up QSAR models. Linear regression analysis showed that classification of metal ions, according to soft or hard ions principle, could improve the relationship. The covalent index X2mr was correlated well to qmax for metal ions containing soft ions. The greater the covalent index value of metal ion was, the greater was potential to form covalent bonds with biological ligands, and the larger was the metal ion biosorption. For metal ions without soft ions, polarizing power Z2/r or the first hydrolysis constant |log KOH| or ionization potential IP were the first three valuable structural parameters to predict qmax. The various expressions of (pseudo) polarizing power, Z2/r, Z/r, Z/r2, Z/AR2 or Z/AR, were also applicable for borderline ions or plus hard ions. However, only Z*2/r considering electron structure of valence shell electron number did not count for the affinity of metal ions by the biomass. This research provided a new way to predict the biosorption capacity of metal ions and to explore the metal-microbe interactions.