Durán N, Bromberg N, Kunz A
Instituto de Química, Biological Chemistry Laboratory, Universidade Estadual de Campinas, SP, Brazil.
J Inorg Biochem. 2001 Apr;84(3-4):279-86. doi: 10.1016/s0162-0134(01)00175-1.
A number of peroxidases, such as lignin peroxidase and manganese peroxidase have proved to be useful for industrial applications. Some studies on the effects of temperature and pH stability have been carried out. It is known that veratryl alcohol increases their stability in the range 28-50 degrees C and is oxidized, leading to veratryl aldehyde formation. Similar results with horseradish peroxidase (HRP) in the presence of cofactors were found, but the oxidation of veratryl alcohol in the absence of cofactors was extremely labile at acid pH and inactivated in a few minutes. Considering the growing industrial application of HRP, knowledge of its stability and denaturation kinetics is required. In this study, horseradish peroxidase pool (HRP-VI) and its isoenzymes HRP-VIII (acid) and HRP-IX (basic) have been shown to catalyze the oxidation of veratryl alcohol to veratryl aldehyde in the presence of hydrogen peroxide at pH 5.8 in the 35-45 degrees C range and in the absence of any cofactors. Heat and pH denaturation experiments in the presence and absence of veratryl alcohol incubation were conducted with HRP-VI and HRP-IX isoenzymes. HRP-IX was the most active isoenzyme acting on veratryl alcohol but HRP-VI was the most stable for the temperature range tested. At 35 degrees C the HRP pool presented decay constant (Kd) values of 5.5 x 10(-2) h(-1) and 1.4 10(-2) h(-1) in the absence and presence of veratryl alcohol, respectively, with an effective ratio of 3.9. These results present a new feature of peroxidases that opens one more interesting application of HRP to industrial processes.
许多过氧化物酶，如木质素过氧化物酶和锰过氧化物酶，已被证明可用于工业应用。已经开展了一些关于温度和pH稳定性影响的研究。已知藜芦醇在28至50摄氏度范围内可提高它们的稳定性，并被氧化，导致藜芦醛的形成。在存在辅因子的情况下，辣根过氧化物酶（HRP）也得到了类似的结果，但在没有辅因子的情况下，藜芦醇在酸性pH下的氧化极其不稳定，几分钟内就会失活。考虑到HRP在工业上的应用日益广泛，需要了解其稳定性和变性动力学。在本研究中，辣根过氧化物酶库（HRP-VI）及其同工酶HRP-VIII（酸性）和HRP-IX（碱性）已被证明在35至45摄氏度范围内、pH为5.8、存在过氧化氢且没有任何辅因子的情况下，可催化藜芦醇氧化为藜芦醛。对HRP-VI和HRP-IX同工酶进行了在有和没有藜芦醇孵育情况下的热变性和pH变性实验。HRP-IX是作用于藜芦醇的活性最高的同工酶，但在测试的温度范围内，HRP-VI是最稳定的。在35摄氏度时，HRP库在没有藜芦醇和存在藜芦醇的情况下，衰变常数（Kd）值分别为5.5×10⁻² h⁻¹和1.4×10⁻² h⁻¹，有效比率为3.9。这些结果呈现了过氧化物酶的一个新特性，为HRP在工业过程中的应用开辟了又一个有趣的方向。
