漆酶降解花生饼中黄曲霉毒素B1 的工艺优化 及分子对接分析Process optimization and molecular docking analysis of laccase degradation of aflatoxin B1 in peanut cake

Abstract

为促进漆酶在花生饼粕中黄曲霉毒素B1（AFB1）脱除中的实际应用，以霉变花生饼为实验对象，利用漆酶降解AFB1，考察加酶量、体系pH、反应温度、反应时间及料液比对AFB1降解率的影响，优化漆酶降解花生饼中AFB1的工艺条件，并通过分子对接分析漆酶与AFB1的相互作用方式。结果表明：漆酶降解花生饼中AFB1的最优工艺条件为加酶量5 U/g、体系pH 6.0、反应时间48 h、反应温度45 ℃、料液比1∶ 10，在此条件下漆酶对花生饼中AFB1的降解率高达83.5%，AFB1残留量为15.8 μg/kg，符合国标要求（≤50 μg/kg）；分子对接分析表明AFB1与漆酶活性空腔中的氨基酸残基His109、Ser110、His111、Ser113、His452、Asp456间形成了氢键网络，漆酶降解AFB1的机制可能与该氢键网络有关。综上，漆酶对花生饼中AFB1具有高效的降解活性，在发霉花生饼脱毒处理中有较大应用前景。In order to promote the practical application of laccase in the removal of aflatoxin B1 (AFB1) in peanut cake/meal, moldy peanut cake was used as the experimental object to degrade AFB1 by laccase. The effects of enzyme dosage, system pH, reaction temperature, reaction time and solid-liquid ratio on the degradation rate of AFB1 were investigated, and the process conditions for the degradation of AFB1 in peanut cake by laccase were optimized. The interaction model between laccase and AFB1 was analyzed by molecular docking. The results showed that the optimal conditions for the degradation of AFB1 in peanut cake by laccase were obtained as follows: enzyme dosage 5 U/g, system pH 6.0, reaction time 48 h, reaction temperature 45 ℃ and solid-liquid ratio 1∶ 10. Under these conditions, the degradation rate of AFB1 in peanut cake was as high as 83.5%, and the residual amount of AFB1 was 15.8 μg/kg, which met the requirements of national standard(≤50 μg/kg). Molecular docking results showed that a hydrogen bond network was formed between AFB1 and the amino acid residues His109, Ser110, His111, Ser113, His452 and Asp456 in the active cavity of laccase. The mechanism of degradation of AFB1 by laccase might be related to the hydrogen bond network. In summary, laccase has high degradability to AFB1, which has great application prospect in detoxification treatment of moldy peanut cake.

Keywords

• 漆酶；花生饼；afb1；分子对接
• laccase; peanut cake; aflatoxin b1;molecular docking