Department of Physical chemistry, Plovdiv University, 24, Tsar Assen st.; BG-4000, Plovdiv, Bulgaria.
Bioelectrochemistry. 2013 Apr;90:1-7. doi: 10.1016/j.bioelechem.2012.09.003. Epub 2012 Oct 9.
The voltammetric studies of Penicillium chrysogenum catalase (PcCAT) adsorbed on spectroscopic graphite, showed direct electron transfer (DET) between its active site and the electrode surface. Analogous tests performed with the commercially available bovine catalase revealed that mammalian enzyme is much less efficient in the DET process. Both catalases were found capable to catalyse the electrooxidation of phenol, but differed in the specifics of catalytic action. At an applied potential of 0.45V the non-linear regression showed the kinetics of the bioelectrochemical oxidation catalysed by the PcCAT obeyed the Hill equation with a binding constant K=0.034±0.002 M(2) (Hill's coefficient n=2.097±0.083, R(2)=0.997), whilst the catalytic action of the bovine catalase was described by the Michaelis-Menten kinetic model with the following parameters: V(max,app)=7.780±0.509 μA, and K(M,app)=0.068±0.070 mol L(-1). The performance of the electrode reaction was affected by the electrode potential, the pH, and temperature. Based on the effect of pH and temperature on the electrode response in presence of phenol a tentative reaction pathway of its bioelectrocatalytic oxidation has been hypothesised. The possible application of these findings in biosensing phenol up to concentration 30 mM at pHs below 7 and in absence of oxidising agents (oxygen or H(2)O(2)) was considered.
青霉细胞色素 c 过氧化氢酶（PcCAT）在光谱石墨上的伏安研究表明，其活性部位与电极表面之间存在直接电子转移（DET）。对市售牛过氧化氢酶进行的类似测试表明，哺乳动物酶在 DET 过程中的效率要低得多。两种过氧化氢酶都能够催化苯酚的电氧化，但催化作用的细节有所不同。在施加的 0.45V 电位下，非线性回归表明 PcCAT 催化的生物电化学氧化动力学符合 Hill 方程，结合常数 K=0.034±0.002 M(2)（Hill 系数 n=2.097±0.083，R(2)=0.997），而牛过氧化氢酶的催化作用则由米氏-门坦动力学模型描述，其参数为：V(max,app)=7.780±0.509 μA 和 K(M,app)=0.068±0.070 mol L(-1)。电极反应的性能受到电极电位、pH 值和温度的影响。基于 pH 值和温度对电极在存在苯酚时的响应的影响，提出了苯酚生物电化学氧化的可能反应途径。考虑了这些发现在生物传感苯酚方面的潜在应用，其浓度可达 30mM，pH 值低于 7，且不存在氧化剂（氧气或 H(2)O(2))。
