果蔬类食品中过氧化氢酶及过氧化物酶的测定方法综述.docx
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果蔬类食品中过氧化氢酶及过氧化物酶的测定方法综述
漯河食品职业学院
[果蔬类食品中过氧化氢酶及过氧化物酶的测定方法综述]
专业：
食品营养与检测
班级：
09级质检六班
学生姓名：
陈文帅
指导教师：
任亚敏
完成时间：
2018年9月4日
摘要
过氧化氢酶是植物体内清除过氧化氢的主要酶类，植物代谢过程会产生活性氧自由基，再转化成过氧化氢，而过氧化氢对植物细胞具有损伤作用。
过氧化氢酶的主要功能即清除植物代谢过程产生的过氧化氢，从而对植物细胞具有保护作用。
过氧化物酶是植物体内重要的呼吸酶类，其活性高低与酚类物质代谢，植物抗性密切相关。
测定过氧化物酶活性能了解植物的进化阶段，以及进化趋势。
更重要的是能确定它在特定环境下的适应能力。
活性高当然抗逆性就越强，反之低就越弱。
在果蔬中的过氧化物酶在热加工中失活时，其他的酶以活性形式存在的可能性是很小的。
通过用荧光法测定植物体中的CAT，了解到一种新的测定果蔬中的CAT。
该方法灵敏度高、实用性强，用于草莓和肥桃中过氧化氢酶活性的测定，获得了满意的结果，是一种可广泛应用于果蔬中过氧化氢酶活性测定的新方法。
对小黑杨、白菜和马铃薯的POD活性的研究发现：
计算POD活性所取最佳时间范围0～60s;合理的H2O2浓度为0.5%～2%，浓度越小，活性越强;缓冲液pH在5.7～7.0均能测出不同植物材料的POD活性，测定结果具有可比性，最适pH为6.0;联苯胺法更为灵敏，但反应产物不太稳定;三氯乙酸终止法不适合某些植物。
关键词：
果蔬过氧化氢酶过氧化物酶荧光测定法愈创木酚法联苯胺法
目录
正文·······································································
第1章绪论····································································
1.1过氧化氢酶································································1
1.1.1过氧化氢酶的定义······················································1
1.1.2简介··································································1
11.1.3触酶································································1
1.1.4来源··································································1
1.1.5H2O2分解酶···························································1
1.1.6过氧化氢酶历史························································2
1.1.7功能··································································2
1.1.8在生物体中的分布与应用···········································2
1.1.9过氧化氢酶检测及反应机制·········································3
1.1.10过氧化氢酶活性的测定方法综述·········································4
1.2过氧化物酶································································4
1.2.1过氧化物酶的定义······················································4
1.2.2简介·····························································5
1.2.3过氧化物酶体·······················································5
1.2.4过氧化物酶体的发现···············································5
1.2.5形态结构·························································6
1.2.6功能反应·························································6
1.2.7动物、植物中的过氧化物酶体······································7
1.2.8进化角度及引发疾病··················································7
1.2.9过氧化物酶活性测定的综述··············································7
1.3本课题研究的意义和所要做的工作···········································8
1.3.1意义··································································8
1.3.2所要做的工作··························································8
第2章过氧化氢酶在果蔬中的测定·············································9
2.1引言·····································································9
2.2过氧化氢酶简介··························································9
2.3实验部分································································9
2.3.1仪器··································································9
2.3.2试剂··································································9
2.3.3实验方法······························································10
2.3.4实验理·······························································10
2.4检测条件的影响··························································10
2．4．1酸度的影响························································10
2．4．2反应时间的影响·····················································10
2．4．3Fe2+浓度的影响······················································11
2．4．4喹啉浓度的影响····················································11
2．4．5CAT的影响··························································11
2．5植物样品中CAT活性的测定···············································11
2.6结论···································································11
第三章过氧化物酶在果蔬中的测定·············································12
3.1引言···································································12
3.2材料与方法······························································12
3.2.1供试材料···························································12
3.2.2试验方法···························································12
3.3结果与分析······························································13
3.3.1不同测定方法、测定POD活性的差异···································13
3.3.2H2O2浓度对POD的影响···············································13
3.3.3pH值对POD的影响··················································13
3.3.4利用三氯乙酸终止法进行的测定········································13
3.4结语·····································································13
第4章总结·····························································14
4.1·········································································14
4.2··········································································14
参考文献····································································15
第一章绪论
1.概述
1.1过氧化氢酶
1.1.1过氧化氢酶的定义
过氧化氢酶（catalase）是催化过氧化氢分解成氧和水的酶，存在于细胞的过氧化物体内。
过氧化氢酶是过氧化物酶体的标志酶，约占过氧化物酶体酶总量的40%。
过氧化氢酶存在于所有已知的动物的各个组织中，特别在肝脏中以高浓度存在。
过氧化氢酶在食品工业中被用于除去用于制造奶酪的牛奶中的过氧化氢。
过氧化氢酶也被用于除去用于制造奶酪的牛奶中的过氧化氢。
过氧化氢酶也被用于食品包装，防止食物被氧化。
1.1.2简介：
HYPERLINK"" 过氧化氢酶的作用是使过氧化氢还原成水:
2H2O2?
O2+2H2O[1]
1.1.3触酶：
过氧化氢酶（CAT）是一种酶类清除剂，又称为触酶，是以铁卟啉为辅基的HYPERLINK"""
1.1.4来源：
几乎所有的生物机体都存在过氧化氢酶。
其普遍存在于能呼吸的生物体内，主要存在于植物的叶绿体、HYPERLINK"" CAT是红血素酶，不同的来源有不同的结构。
在不同的组织中其活性水平高低不同。
过氧化氢在肝脏中分解速度比在脑或心脏等器官快，就是因为肝中的CAT含量水平高。
1.1.5H2O2分解酶：
这是一种稳定的过氧化氢分解酶,能将过氧化氢分解成水和氧气,而对纤维和染料没有影响,因而漂白后染色前,通过H2O2分解酶去除漂白织物上和染缸中残留的过氧化氢,以避免纤维的进一步氧化和染色时染料的氧化。
同时能缩短加工时间,减少水洗用水,降低废水量。
尤其对纱线、筒子纱和针织物更为适用。
同样,过氧化氢分解酶随pH值和温度的改变,其活力随之变化,在pH7左右和30～40?
活性最大。
过氧化氢浓度增大,会加快分解反应速度,但必须注意当浓度大于一定量时,酶的作用将减弱,这样过多的残留H2O2对纤维和染料是不利的。
所以不能因为有了H2O2分解酶,就能任意地加大H2O2的用量。
使用时,通常要注意H2O2分解酶对常用表面活性剂和H2O2稳定剂的相容性,实际生产应用pH为6～8,温度20～55?
酶用量5～10KCLU/升,时间10～20min。
此技术已慢慢地被国内所认识和接受,它对提高活性染料色泽鲜艳度很有利。
1.1.6过氧化氢酶历史：
作为一种物质，过氧化氢酶是在1811年被过氧化氢（H2O2）的发现者泰纳尔（LouisJacquesThanadar）首次发现。
1900年，OscarLoewe将这种能够降解过氧化氢的酶命名为“catalase”，即过氧化氢酶，并发现这种酶存在于许多植物和动物中。
1937年，詹姆斯·B·HYPERLINK""
1.1.7功能：
过氧化氢是一种HYPERLINK"" 但过氧化氢酶真正的生物学重要性并不是如此简单：
研究者发现HYPERLINK" 一些人群体内的过氧化氢酶水平非常低，但也不显示出明显的病理反应。
这很有可能是因为正常HYPERLINK" 过氧化氢酶通常定位于一种被称为HYPERLINK""""" 但细胞被HYPERLINK""""""
1.1.8在生物体中的分布与应用：
过氧化氢酶存在于所有已知的动物的各个HYPERLINK""beetle）中，过氧化氢酶具有独特用途。
这种甲虫具有两套分开储存于腺体中的化学物。
大的腺体中储存着HYPERLINK"" 过氧化氢酶也普遍存在于植物中，但不包括真菌，虽然有些真菌被发现在低pH值和温暖的环境下能够产生该酶。
绝大多数需氧微生物都含有过氧化氢酶[4]。
例外包括Streptococcus，一种没有过氧化氢酶的需氧HYPERLINK"barkeri，也含有过氧化氢酶。
相关疾病：
HYPERLINK"disorder）过氧化物酶缺乏症（acatalasia）是由过氧化氢酶功能缺陷所造成的。
应用：
过氧化氢酶在食品工业中被用于除去用于制造HYPERLINK""" 过氧化氢酶在实验室中还常常被用作了解酶对反应速率影响的工具。
1.1.9过氧化氢酶检测及反应机制：
进行中的过氧化氢酶检测，可以观察到气泡。
过氧化氢酶检测是微生物学家鉴定细菌种类的主要的三种检测手段之一，即用过氧化氢来检测过氧化氢酶是否存在。
假如细菌中含有过氧化氢酶，则在HYPERLINK" 有气泡生成，则该菌被认为是呈“过氧化氢酶阳性”。
如staphylococcus和micrococcus。
没有，则该菌被认为是呈“过氧化氢酶阴性”。
如streptococcus和enterococcus。
虽然过氧化氢酶检测无法鉴定特定生物体，但与其他检测方法结合，它可以有效地帮助诊断。
此外细菌中是否存在过氧化氢酶，还取决于细胞生长条件和所使用的培养基。
反应机制：
虽然过氧化氢酶完整的催化机制还没有完全被了解，但其催化过程被认为分为两步：
H2O2+Fe（III）-E?
H2O+O=Fe（IV）-E（.+） H2O2+O=Fe（IV）-E（.+）?
H2O+Fe（III）-E+O2[12] 其中，“Fe（）-E”表示结合在酶上的血红素基团（E）的中心铁原子（Fe）。
Fe（IV）-E（.+）为Fe（V）-E的一种共振形式，即铁原子并没有完全氧化到+V价，而是从血红素上接受了一些“支持电子”。
因而，反应式中的血红素也就表示为自由基阳离子（.+）. 过氧化氢进入活性位点并与酶147位上的天冬酰胺残基（Asn147）和74位上的组氨酸残基（His74）相互作用，使得一个质子在氧原子间互相传递。
自由的氧原子配位结合，生成水分子和Fe（IV）=O。
Fe（IV）=O与第二个过氧化氢分子反应重新形成Fe（III）-E，并生成水分子和氧气。
[12]活性中心铁原子的反应活性可能由于357位上酪氨酸残基（Tyr357）的苯酚基侧链的存在（帮助Fe（III）氧化为Fe（IV））而得以提高。
反应的效率可能是通过His74和Asn147与反应中间体作用而得以提高。
该反应的速率通常可以通过米氏方程来确定。
过氧化氢酶也能够氧化其
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