Talk:Catalase

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I would like to know which living creature produces most catalase and water in its life span and which produces more water than it consumes. Thank you.

What's the main difference between peroxidases and catalase?

Contents 1 difference between peroxidases and catalase 2 5 Million? 30,000,000? Both? Neither? 3 Protection 4 Catalase test 5 optimum temperature for catalase activity 6 The first sentence after the "Role in organs" 7 Could you list every cell that has catalase in it?

[edit] difference between peroxidases and catalase

Catalase is unique in its potential to catalyse 2 reactions: i) decomposition of hydrogen peroxide into water and oxygen; ii) oxidation of a substrate (hydrogen donor) with the help of hydrogen peroxide. Hydrogen donors for catalase are ethanol (drink alcohol), methanol, and laboratory reagents that are used to demonstrate the peroxidatic activity of the enzyme. Best known among the latter is diaminobenzidine, which forms an insoluble polymer that is brown when oxidized. Since it is insoluble, it precipitates exactly where catalase is localized, and thus shows in the microscope the exact location of the enzyme in the cell. This stain which is very reliable if carried out correctly, has been used by many investigators to identify and study the peroxisomes, since these organelles in normal conditions contain a lot of catalase. Peroxidases can carry out only the second kind of reaction, that is: oxidizing a hydrogen donor. Many of them can be localized with diaminobenzidine too. There are many different peroxidases, that is their pH optimum, resistance to chemicals and temperature differ. However some peroxidases have very specific substrates, for example glutathione (GSH) peroxidase does not react with diaminobenzidine; it protects the cell against hydrogen peroxide but destroy GSH that must be regenerated at the expense of energy. Another specific peroxidase is found in the thyroid epithelial cell: it binds iodium to thyreoglobuline, and this reaction results in the active thyroid hormone. Peroxidases are found in milk (lactoperoxidase), saliva (probably also lactoperoxidase), tears (lacrimal gland), in granular leucocytes (myeloperoxidase and eosinophil peroxidase), macrophages, blood platelets, uterine epithelium, and many other cell types. The best known plant peroxidase is horseradish peroxidase (HRP) that is a common laboratory reagent; when coupled to antibodies, these are subsequenlty demonstrated and localized through a peroxidatic reaction (with diaminobenzidine, for ex). Frank Roels, August 25th, 2005.

[edit] 5 Million? 30,000,000? Both? Neither?

I've been researching catalase and keep coming up with conflicting figures. Everyone says "it's one of the most efficient enzymes," but after that, numbers diverge. In this article alone, it is purported to "convert 5 million molecules of hydrogen peroxide to water and oxygen each minute" and "500,000/second." Which is it? Are the numbers refering to two different things, maybe? If so, can we clarify that in the article a little better? Also, sources?

Thanks for your time.

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This page quotes M.B.V. Roberts, author of "Biology A Functional Approach" as saying that catalase has a turnover number of 6 million/min

Kb ganesh 18:18, 29 August 2006 (UTC)

I think part of the problem is that there are different kinds of catalase. Another problem is that the rate of reaction is heavily influenced by the conditions in which it occurs. I'll work on making this clear in the article. Galanskov 01:57, 12 February 2007 (UTC)

[edit] Protection

Please semiprotect this page. It has been a target of vandalism by someone by the IP 85.12.64.148. --Gray Porpoise 17:26, 28 June 2006 (UTC)

[edit] Catalase test

The catalase test bit doesn't really explain what it's for very well. A biologist of any calling will probably have no problem guessing what it's for with the info currently given but someone else might go, what the heck? Nil Einne 14:37, 11 October 2006 (UTC)

[edit] optimum temperature for catalase activity

I would like to know the temperature at which catalase activity is optimized. Is it significantly different for human catalase as opposed to the catalase found in bovines? —The preceding unsigned comment was added by 207.71.230.77 (talk) 05:33, 12 December 2006 (UTC).

[edit] The first sentence after the "Role in organs"

This sentence used to be: Hydrogen peroxide is formed as a waste product of metabolism in many living organisms It is now: Hydrogen peroxide is not as a neverof metabolism in many dead organisms. I believe that the previous edition is correct, but I don't know much about biology. Maybe the editor didn't know much english. —The preceding unsigned comment was added by 66.67.107.143 (talk) 00:27, 13 December 2006 (UTC).

I noticed that, and im wondering if we should change it back, the change looks like vandalisation to me Atlasrune 18:10, 15 December 2006 (UTC) Yes it most definetly is vandalism--Max Randor 19:40, 1 February 2007 (UTC) already has been fixed --Max Randor 19:42, 1 February 2007 (UTC)

[edit] Could you list every cell that has catalase in it?

Is it clear the number of cells that have catalase in it? I think people come out of microbiology after they learn about staph aureus and the catalase test used to distinguish it and think that it is one of the few "cells" organisms that have catalase and maybe it should be emphasized more that a lot of cells have catalase in them. An exhaustive list would be cool but maybe impossible (?). —The preceding unsigned comment was added by 207.151.236.42 (talk) 22:41, 28 January 2007 (UTC).