【摘要】 为了了解稀土元素与酶相互作用的化学机理,用紫外-可见(UV-Vis)吸收光谱技术和电化学方法研究了La3+与过氧化物酶(POD)的模型化合物,微过氧化物酶-8(MP-8)或微过氧化物酶-11(MP-11)的相互作用机理.La3+优先与MP-8或MP-11分子中血红素卟啉环上的2个丙酸基团的羰基氧发生键合作用,使它们的聚集程度降低,卟啉环的非平面性增加.由于MP-8分子聚集的倾向要小于MP-11,La3+使MP-8聚集程度的降低和卟啉环非平面性增加的程度要大于MP-11.由于MP-11的肽链较长而能形成螺旋状构象,使肽链上的羰基基团被包埋在肽链的疏水基团中,因此,La3+与MP-11中肽链上的羰基氧基本上不能发生键合作用.而MP-8的肽链较短,不能形成螺旋状结构,La3+也能与肽链上的羰基氧发生键合作用.更多还原

【Abstract】 In order to understand the chemical mechanism of the interaction of the enzymes with the rare earth elements, the mechanism of the interaction between La3+ and the model of POD, MP-8 or MP-11 was studied using UV-Vis absorption spectroscopy and electrochemical technique. It was found that La3+ was bound firstly to the carbonyl oxygen of the metacetonic acid group in the heme group of the MP-8 or MP-11 molecule, resulting in the decrease of their aggregation extents and the increase of the non-planarity of the porphyrin group. The decrease extent of the aggregation of the molecules and then the increase extent of the nonplanarity of the porphyrin group for MP-8 due to La3+ binding were greater than those for MP-11 be-cause the aggregation tendency of MP-8 was less than that of MP-11. The peptide of MP-11 was long enough to form the helical conformation, thus, the carbonyl oxygen in the peptide would be embedded in the hydrophobic microenvironment of the peptide, and La3+ was not easy to coordinate with the carbonyl oxy-gen in the peptide of MP-11. However, the peptide of MP-8 was relatively short, it could not form the helical conformation and therefore, La3+ was easy to interact with the carbonyl oxygen in the peptide of MP-8.更多还原