GC: n
S: BIOCHEMC – http://www.worthington-biochem.com/ctl/default.html (last access: 26 October 2017); PDB – http://pdb101.rcsb.org/motm/57 (last access: 26 October 2017).
N: 1. Comes from Latinized form of Greek katalysis “dissolution, a dissolving” (substances, military governments, etc.), from katalyein “to dissolve,” and from kata “down”.
2. Catalase is a red crystalline enzyme that consists of a protein complex with hematin groups and catalyzes the decomposition of hydrogen peroxide into water and oxygen.
3. Deficiency of catalase was discovered by ear, nose and throat surgeon Professor Takahara at the Okayama University Medical School.
4. The ability of catalase to perform its functions is derived from its unique structure which evolved due to the necessity of aerobic organisms to get rid of hydrogen peroxide in order to preserve life.
5. An NADPH (nicotinamide adenine dinucleotide phosphate) ligand with a high reduction potential is embedded into the structure of catalase to guard the enzyme from inactivation by its own highly oxidizing substrate
6. Types of catalase:
- Monofunctional catalases: The dismutation of hydrogen peroxide is their predominant activity and any peroxidatic activity is minor and restricted to small substrates. The most convenient way of subcategorizing this group is based on subunit size with an accompanying attention to heme content. This gives rise to two subgroups, one containing small subunit enzymes (55 to 69 kDa) with heme b associated, and one containing large subunit enzymes (75 to 84 kDa) with heme d associated. The monofunctional catalases characterized in greatest detail have all proved to be active as tetramers, although dimeric, heterotrimeric, and hexameric enzymes have been reported, but never conclusively characterized.
- Catalase-peroxidases: They exhibit a significant peroxidatic activity in addition to the catalatic activity. They have been characterized in both fungi and bacteria and resemble certain (type I) plant and fungal peroxidases in sequence. There is more uniformity in sequence within this group of catalases, which contain heme b, have subunits larger than 80 kDa (with a few exceptions), and are active as either dimers or tetramers.
- Nonheme catalases: This smallest group, there are only three nonheme cata- lases so far characterized and an equal number sequenced, all of bacterial origin (Lactobacillus plantarum, Thermoleophilum album, and Thermus thermophilus). The active site of each of the three enzymes contains a manganese-rich reaction center rather than a heme group, and it was this lack of a heme that led to them originally being called “pseudo-catalases.”
- Minor catalases: Several heme-containing proteins, including most peroxidases, have been observed to exhibit a low level of catalatic activity, with the chloroperoxidase from Caldariomyces fumago exhibiting the greatest reactivity as a catalase.
7. Acatalasemia is the inherited near-total deficiency of catalase activity in red blood cells, will inevitably result in a variety of health problems for an individual.
S: 1. OED – https://www.etymonline.com/search?q=KATALYSIS (last access: 26 October 2017). 1 & 2. MW – https://www.merriam-webster.com/dictionary/catalase (last access: 26 October 2017). 3 to 5. CHEMISTRY – http://chemistry.berea.edu/~biochemistry/2016/lipoamide/ (last access: 26 October 2017). 6. GEOMICALS – https://www.researchgate.net/publication/229339112_Enzymology_and_structure_of_catalases (last access: 26 October 2017). 7. CHEMISTRY – http://chemistry.berea.edu/~biochemistry/2016/lipoamide/ (last access: 26 October 2017).
SYN:
S:
CR: acatalasemia
