生物酶对废纸浆过氧化氢漂白的影响

研究了过氧化氢酶及辣根过氧化物酶对废纸浆过氧化氢漂白的影响。结果表明：在碱性条件下,两种酶的存在加剧了过氧化氢的分解,且过氧化氢酶催化分解过氧化氢的能力要强于辣根过氧化物酶。     

用721-分光光度计测定过氧化氢酶活性的新方法

本研究采用两步法对过氧化氢酶活力进行测定。第一步是经典滴定法中的过氧化氢酶与底物作用，第二步采用过氧化物酶与剩余过氧化氢反应，氧供体（DH2）被氧化成棕色物，以棕色深浅反推过氧化氢酶活力单位。结果表明，该方法是一种灵敏、实用的测定过氧化氢酶活性的新方法。     

重组过氧化氢酶与一种商品过氧化氢酶的性质比较

将重组过氧化氢酶和市售一种商品过氧化氢酶的性质进行了比较。重组酶的最适温度为70℃，某商品过氧化氢酶的最适温度为40℃；与这种商品过氧化氢酶相比，重组酶的热稳定性更好。重组过氧化氢酶和这种商品过氧化氢酶的最适pH都是7．0；重组酶和这种商品过氧化氢酶在pH3-8的范围内均较为稳定；重组酶在室温放置1个月后酶活力基本保持不变，而此种商品过氧化氢酶活力损失约70％；金属离子对重组酶和这种商品过氧化氢酶都有抑制作用，抑制程度有所不同；EDTA抑制这种商品过氧化氢酶的活性，但不抑制重组酶的活性。     

过氧化氢酶的检测、控制和应用

详细介绍了过氧化氢酶的特性、检测方法,过氧化氢酶对生产的影响及控制方法,以及过氧化氢酶的用途。     

宠物咬胶用漂白牛皮中过氧化氢残留量测定及分解研究

目的探究不同温度、过氧化氢酶浓度、反应时间等对牛皮中过氧化氢分解速率的影响规律,以此指导生产中如何控制狗咬胶中过氧化氢残留量超标的问题。方法以生产宠物狗咬胶的漂白牛皮为原料,通过采用不同温度(30~70℃)的水和不同浓度(3%~5%)的过氧化氢酶溶液进行处理,对处理后的过氧化氢残留量进行测定。结果采用50℃温水浸泡漂白牛皮可以较快地去除其中残留的过氧化氢;或者采用浓度为3%的过氧化氢酶溶液,40~50℃,浸泡30 min左右可以更快地去除过氧化氢。根据处理条件的不同,通过试验拟合出方程可以比较准确地计算去除漂白牛皮样品中残留过氧化氢所需要的大体时间。结论通过热处理或者过氧化氢酶溶液处理,能够有效降低漂白牛皮中残留的过氧化氢含量,使最终产品符合要求。     

原料乳中过氧化氢酶定性检测方法的研究

为了监控原奶中是否掺有过氧化氢酶，采用人为添加过氧化氢到原奶中的方法，利用双氧水剂试纸条法测定，通过检测结果的判定，确定原奶中是否添加过氧化氢酶。结果表明，添加有过氧化氢酶的原奶，在用双氧水试纸条检测时为阴性，未添加过氧化氢酶的原奶，在用双氧水试纸条检测时为阳性。该方法用于实际原奶样、奶车样、奶仓样的检测，结果令人满意，检出限6mg／kg。     

火龙果过氧化氢酶活性的研究

以火龙果中的过氧化氢酶(CAT)为研究对象,对其酶的活性变化及其特性的研究表明,火龙果中的过氧化氢酶的最适温度为30℃,最适pH为7.0.甲醇和乙醇对火龙果中过氧化氢酶活性的影响均表现为低浓度对该酶具有激活作用,高浓度转为抑制作用.金属离子Cu2 对该酶有不同程度的激活作用,而Mn2 和Na 则对该酶有一定程度的抑制作用.     

过氧化氢酶的功能及研究

过氧化氢酶是一类广泛存在于动物、植物和微生物体内的氧化酶,其功能是催化细胞内过氧化氢分解,防止氧化。在论述过氧化氢酶类型划分、结构特点及生理功能的基础上,对其分离纯化、活性测定、性质研究做了综述。     

一种测定蜂蜜中过氧化氢酶活性的改进方法

过氧化氢是蜂蜜的主要抑菌成分之一,其抑菌活性与蜂蜜中过氧化氢酶密切相关。过氧化氢酶在蜂蜜中普遍存在,建立测定方法对评价蜂蜜抑菌活性和内在质量有重要意义。实验参照Huidobro等人的方法,对蜂蜜中过氧化氢酶活性的测定方法进行了改进,并测定了5种单花种蜂蜜中过氧化氢酶的活性。结果表明,不同种类的单花种蜂蜜中过氧化氢酶活性存在较大差异,湖北荆州油菜蜜的过氧化氢酶活性最高,为(204.3±3.8)×10-3/(min·g),河北石家庄产的枣花蜜的酶活性最低,仅为(8.1±0.6)×10-3/(min·g)。中国蜂蜜中的过氧化氢酶的活性因蜂蜜种类、产地不同存在较大差异。     

过氧化氢酶去除漂白残留过氧化氢工艺的研究

本文采用过氧化氢酶去除过氧化氢漂白棉针织物时残留的过氧化氢,通过单因素实验分析,确定影响过氧化氢酶去除残留过氧化氢工艺的最适条件为:p H值7~8,过氧化氢酶用量0.1 g/L,温度20℃,处理15min,浴比1∶15。     

Effects of H2O2 under low- and high-aeration-level conditions on growth and catalase activity in Exiguobacterium oxidotolerans T-2-2T

The effects of H2O2 under low- and high-aeration-level conditions on growth and catalase activity in Exiguobacterium oxidotolerans T-2-2T were investigated. Continuous addition of 5-200 mM H2O2 to the culture medium from the mid-exponential growth phase enhanced the growth of the strain under the low-aeration-level condition, whereas the addition of 5-50 mM H2O2 decreased intracellular specific catalase activity and extracellular total catalases activity. The detection of extracellular catalase by the cells and the decrease in intracellular specific catalase activity and extracellular total catalase activity under the high-aeration-level condition account for the stimulation of growth by the introduced H2O2 and the decrease in catalase activities induced by O(2) from H2O2 in the medium. On the other hand, the addition of H2O2 to the medium prior to the initiation of growth inhibited the growth but increased the specific activity of intracellular catalase in the stationary growth phase. Strain T-2-2T grew when 10 mM H2O2 was added to the medium prior to growth. However, the growth was completely inhibited by the catalase inhibitor 3-amino-1,2,4-triazole (3-AT). The continuous addition of H2O2 at an appropriate concentration from prior to the initiation of growth to the stationary growth phase under the low-aeration-level condition resulted in higher intracellular specific catalase activity and cell growth rate than single H2O2 addition prior to growth.     

烟草与黄瓜花叶病毒互作中过氧化氢酶活性的变化

研究了12个不同抗性水平的烟草品种接种黄瓜花叶病毒前后过氧化氢酶活性的动态变化及其与烟草抗病性的关系。结果表明,接种病毒后抗、感品种的过氧化氢酶活性总体水平比对照降低,但酶活性的动态变化规律与烟草抗病性之间的相关性并不显著。利用DPS数据处理系统分析表明:酶活性变化差值及其平均值与病情指数之间均不存在显著相关性,说明以接种前后植物体内酶活性的变化值作为抗病性鉴定的指标在烟草-黄瓜花叶病毒体系中是不可行的。     

Effect of nitrate and incubation conditions on the production of catalase and nitrate reductase by staphylococci

The objective of this work was to study the production of catalase and nitrate reductase by staphylococci in order to understand their role in lipid oxidation during sausage manufacturing. Catalase and nitrate reductase were measured in resting cells and supernatants of staphylococci grown in different conditions. All staphylococci (except S. warneri) synthetized nitrate reductase. In static condition, the synthesis was maximal during exponential growth phase, whereas in shaking condition, the synthesis was maximal at the beginning of stationary phase. The production of nitrate reductase was increased in presence of nitrate, this effect was particularly important for the two S. carnosus strains which exhibited the highest activity. For all staphylococci, the production of catalase was maximal at the end of the exponential growth phase. The lowest amount of catalase was produced by S. warneri and the highest by S. carnosus. Only S. xylosus 873 and S. saprophyticus 852 released high amounts of catalase in the supernatant growth. Staphylococci produced higher amounts of catalase in shaking conditions. Addition of nitrate in the growth media favoured the synthesis of catalase, with a pronounced effect for S. carnosus. Nitrate also favoured the release of catalase.     

Cloning and high expression of catalase gene from bacillus sp. TE124

An efficient expression system for producing catalase in Bacillus was developed. A catalase was purified from Bacillus sp. TE124 and the catalase gene was cloned by plaque hybridization with a probe constructed from the N-terminal amino acid sequence of the enzyme. The gene, containing an open reading frame of 1452 bp, was subcloned into pHY300PLK for self-cloning into the organism. As a result, the production of catalase increased 20-fold over that of the parent strain.     

Catalase Activity for Rapid Assessment of High Level Total Mesophilic Microbial Load in Milk

ABSTRACT: Total mesophilic microbial load (APC) is an important index for milk quality. It takes 48 h to enumerate APC with conventional plating methods. This report presents a rapid catalase activity test for monitoring APC in milk. Most aerobic microorganisms have strong catalase activities. Catalase activity in milk was monitored with a Pasteur pipette method in 5 min. The correlation between high APC numbers (> 4.0 log CFU/ml) and catalase activities was strongly correlated with r²=0.89. Classifying the APC into eight contamination groups was found to be a sound means of utilizing the resultant catalase activities to predict APC.     

Purification of Milk Catalase by Immunoaffinity Chromatography

Antiserum against commercially available bovine liver catalase was prepared in rabbits. Anti-catalase antibody in serum was prepared following 30% ammonium sulfate treatment and Sephacryl S-300 column chromatography. The anti-catalase antibody was coupled to cyanogen bromide-activated Sepharose 4B, and using this immunoadsorbent crude milk catalase was purified. About 7.0 mg pure catalase was produced from 10 kg milk. Activity of the purified products was about 2.58 × 10⁴ times as pure as cows' milk. The purified catalase was electrophoretically homogeneous, appearing as a single band.     

Cloning and expression analysis of two catalase genes from Aspergillus oryzae

Fungi contain distinct genes encoding the same class of enzyme that are differentially regulated according to conditions. We cloned two catalase genes, catA and catB, from Aspergillus oryzae. The catA gene predicts a 747-amino-acid polypeptide sharing 81% identity with Aspergillus fumigatus catalase (catA) and 77% with Aspergillus nidulans catalase (catA). The catB gene predicts a 725-amino-acid polypeptide sharing 82% identity with A. fumigatus catalase (catB) and 75% with A. nidulans catalase (catB). However, the catA and catB genes share little homology (41%) with one another, suggesting that each gene belongs to a distinct gene family. Overexpression studies demonstrated that both genes encode a functional catalase. Promoter assays indicated that the catA gene is developmentally regulated as it was preferentially expressed in solid-state cultures undergoing sporulation. However, its expression was not affected by hydrogen peroxide treatment. Conversely, the catB gene was highly expressed under all culture conditions tested, and it was induced by hydrogen peroxide treatment. These results suggest that the catB gene may be mainly used for detoxification of oxidative stress while the catA gene may have another role such as chaperoning proteins in the spore.     

Heat Inactivation of Catalase from Cod Muscle and from Some Psychrophilic Bacteria

Catalase from Pseudomonas sp. and Micrococcus sp. bacteria is inactivated at 93°C and 73°C, respectively, while cod muscle catalase is inactivated at 41°C. This implies that a suitable thermal treatment of a mixture of cod muscle and bacterial catalases will destroy only the cod catalase and leave the bacterial catalase unaltered. The activity of the remaining bacterial catalase is then measured using the disc flotation method.     

H2O2 tolerance of Vibrio rumoiensis S-1(T) is attributable to the cellular catalase activity

The extraordinarily high level of H2O2 tolerance of Vibrio rumoiensis strain S-1(T) when compared with the tolerance levels of strain S-4, a probable catalase-deficient derivative of strain S-1(T), was demonstrated by the introduction of 0-100 mM H2O2 during the mid-exponential growth phase. The contribution of catalase to the H2O2 tolerance was also demonstrated by comparing the catalase-deficient mutant Escherichia coli strain UM2 with a UM2 strain, harboring the plasmid pBSsa1, which carried the strain S-1(T) catalase gene vktA. The decomposition rates of 23-25 mM H2O2 that was introduced in the culture fluids of strain S-1(T) and E. coli UM2 harboring pBSsa1 corresponded to the calatase activities of the cells by spectrophotometric measurements. The presence of cell surface catalase was observed by immunoelectron microscopy, using an antibody for intracellular catalase in strain S-1(T). The high level of H2O2 tolerance of strain S-1(T) was attributable to the catalase activity of the cells. Cell surface catalase is considered to contribute to the catalase activity of strain S-1(T) cells.