Product Overview
Background
Catalase is present in the peroxisomes of nearly all aerobic cells and serves to protect the cell from the toxic effects of hydrogen peroxide by catalyzing the decomposition of H2O2 (1,2). The mechanism of catalysis is not fully elucidated, but the overall reaction is as follows:2H2O2 —> 2H20 + O2Catalase has one of the highest catalytic activities reported, near the diffusion-controlled limit. Catalases are tetramers of four identical subunits (220 to 350 kD), each with a heme prosthetic group at the catalytic center. Eukaryotic catalases bind NADPH, which helps to stabilize the enzyme (3).In humans, the highest levels of catalase are found in the liver, kidney, and erythrocytes, where it is believed to account for the majority of hydrogen peroxide decomposition. Studies in a mouse model system have demonstrated the importance of catalase in preventing methemoglobin formation in erythrocytes (4). Catalase activity can be directly monitored in the ultraviolet region (7), however the UV assay is subject to interference due to absorption by protein and other components in biological samples.
Assay Principle
This colorimetric, cuvette based catalase assay involves two steps. Since the rate of dismutation of hydrogen peroxide to water and oxygen is proportional to the concentration of catalase, samples are first incubated with a known amount of hydrogen peroxide. The remaining hydrogen peroxide, following a fixed incubation period, is then determined by the oxidative coupling reaction of 4-aminophenazone (4-aminoantipyrene, AAP) and 3,5-dichloro-2-hydroxy-benzenesulfonic acid (DHBS) in the presence of H2O2 and catalyzed by horseradish peroxidase (6). The resulting quinoneimine dye is measured at 520nm.Notes: Catalase is very unstable at high dilution and should be kept cold and assayed within 30-60 minutes after dilution. Whole blood samples may be stored at 4°C for up to two weeks but it is recommended that samples be stored at –70°C for long-term storage. Red blood cell lysates, undiluted, are stable for 5 days at 4°C. Long term storage should be at –70°C.
References1. Deisseroth, A. & Dounce, A.L., Physiol. Rev. 50, 319-375 (1970).2. Zamocky, M. & Koller, F. Prog. Biophys. Mol. Biol. 72, 19-66 (1999).3. Kirkman, H.N., et al., , J. Biol. Chem. 262, 660-666 (1987).4. Wakimoto, M., et al., Acta Med. Okayama 52, 233-237 (1998).5. Aebi, H. Methods Enzymol 105, 121-126 (1984).6. Fossati, P., et.al. Clin. Chem. 26, 227-231 (1980).
Product Documents
ebiomall.com
>
>
>
>
>
>
>
>
>
>
>
>
缺点是人工计数可能发生的随机误差较大。
需要做脂肪代谢实验，打算通过在心肌新鲜组织匀浆中加入核素标记的脂肪酸代谢底物（[14C]-Palmitate），通过液体闪烁计数仪测定氧化产物[14C]CO2的放射性计数来反应脂肪酸的氧化代谢率。但是实验室只有γ放射免疫计数仪，请问能否用其测量“软β射线”14C；仪器需要作何调整吗？？？
********
别告诉我计数的方法用数，我今天早上数了0.4g的微丸，近1000粒，快成熊猫，差点被送动物园了。也别告诉我测微丸的粒径用尺子量，我可是想着把它们排成一条线（增加准确度，可以避免忽略小粒子）再量，可是，这些小粒子不像《花园宝宝》里的小点点们那样听话，他们不爱排队。
各位老师是否还有什么高招？小的在这请教了。
能不能用kappa检验，我看了论坛上的帖子，好像是不行的。但是看到一篇文章，计数资料却用了kappa检验，请问能否这样使用，如果能的话，应该用什么软件，怎么计算。谢谢
提到的文章见后
文章.rar(267.87k)
求助原因：论文答辩
你参与的主要专业版面（必填）：预防医学与医学统计讨论版
试验或调查设计类型：病例对照研究
本次分析的主要目的：了解不同病某些共同症状的变化差异。
数据类型及变量的说明：y：病1，病2；X1：症状1（0/1）；……症状i（0/1）;X2：不同时间，day1....dayi
拟采用的分析方法：?。
主要存在的问题：版上讨论的计量RM资料分析较多，但对于计数资料(0,1);重复测量(day1-i)，该用什么方法怎么分析？此外，想知道不同时间的症状差异如何分析？
求助者email：minw@sohu.com
频率，是单位时间内完成周期性变化的次数，是描述周期运动频繁程度的量，常用符号f或ν表示，单位为秒分之一，符号为s。为了纪念德国物理学家赫兹的贡献，人们把频率的单位命名为赫兹，简称"赫"，符号为Hz。每个物体都有由它本身性质决定的与振幅无关的频率，叫做固有频率。频率概念不仅在力学、声学中应用，在电磁学、光学与无线电技术中也常使用。
