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Catalase is a common enzyme found in nearly all living organisms exposed to oxygen ... Hydrogen peroxide is naturally produced by the body and broken down by catalase.
However the last enzyme is absent in humans, explaining the disease known as gout, caused by the accumulation of uric acid. Certain enzymes within the peroxisome, by using molecular oxygen, remove hydrogen atoms from specific organic substrates (labeled as R), in an oxidative reaction, producing hydrogen peroxide (H 2 O 2, itself toxic):
A peroxisome is a type of microbody that functions to help the body break down large molecules and detoxify hazardous substances. It contains enzymes like oxidase, react hydrogen peroxide as a byproduct of its enzymatic reactions. Within the peroxisome, hydrogen peroxide can then be converted to water by enzymes like catalase and peroxidase.
The cytosols of virtually all eukaryotic cells contain a SOD enzyme with copper and zinc (Cu-Zn-SOD). For example, Cu-Zn-SOD available commercially is normally purified from bovine red blood cells. The bovine Cu-Zn enzyme is a homodimer of molecular weight 32,500. It was the first SOD whose atomic-detail crystal structure was solved, in 1975. [10]
It forms white, raised, cohesive colonies about 1–2 mm in diameter after overnight incubation, and is not hemolytic on blood agar. [5] It is a catalase-positive, [10] coagulase-negative, facultative anaerobe that can grow by aerobic respiration or by fermentation. Some strains may not ferment. [3] [11]
The main criterion for differentiation between Staphylococcus spp. and Streptococcus spp. is the catalase test. Staphylococci are catalase positive whereas streptococci are catalase-negative. [2] S. pyogenes can be cultured on fresh blood agar plates.
In today's puzzle, there are nine theme words to find (including the spangram). Hint: The first one can be found in the top-half of the board. Here are the first two letters for each word: MI. CE ...
For many of these enzymes the optimal substrate is hydrogen peroxide, but others are more active with organic hydroperoxides such as lipid peroxides. Peroxidases can contain a heme cofactor in their active sites, or alternately redox-active cysteine or selenocysteine residues. The nature of the electron donor is very dependent on the structure ...