高压处理对辣根过氧化物酶活性及构象的影响

摘要

高压处理对果蔬过氧化物酶活性的钝化程度会影响果蔬的感官品质和贮藏期,有必要研究高压条件下过氧化物酶的结构变化与其活性的关系。采用圆二色谱法和荧光光谱法,研究了室温下,100、300、500MPa压力分别处理15min对辣根过氧化物酶二级、三级结构及活性的影响。结果表明：高压处理对辣根过氧化物酶（HRP）有钝化作用,随着处理压力的增加,HRP的活性依次下降2.36%、5.69%、10.36%,HRP较耐压;HRP的α-螺旋、β-折叠和无规卷曲含量的升幅均小于4%,β-转角含量显著下降,且下降程度均达到11%;高压处理后的HRP在234nm激发光谱和308nm发射光谱特征峰的荧光强度下降,下降程度依次为18.28%、5.46%和4.04%,且100MPa压力下处理的HRP荧光强度下降的程度最大。说明高压处理对HRP有钝化作用,且与其二级和三级结构的变化有关。%High pressure treatment on the activity of peroxidase in fruits and vegetables can affect the sensory quality and shelf life of fruit and vegetable products,and thus it is necessary to study the relationship between the changes of peroxidase activity and its structure under the conditions of high pressure.Circular dichroism（CD）and fluorescence spectrometry（FP） were used to study the effect of high pressure treatment at 100,300,500 MPa for 15 min at room temperature on the secondary and tertiary structure of horseradish peroxidase（HRP） and its activity.The results showed that HRP was pressure-resistant and HRP activities were decreased respectively by 2.36%,5.69% and 10.36% with the increase of the above pressure.The contents of α-helix,β-sheet and random coils in HRP were all increased by less than 4%,while the content of β-turn was significantly decreased by over 11%.After HRP was processed by high pressure,the HRP fluorescence intensities at the excitation spectra peak of 234 nm and emission spectra peak of 308 nm were decreased respectively by 18.28%,5.46% and 4.04%.The fluorescence intensity of HRP treated at 100 MPa,15 min was decreased to the largest extent.The results showed that high pressure processing obviously inactivated the activity of horseradish peroxidase that was related to its structural changes.