Re: Is there different amounts of catalase in different vertebrae?

Hi Hanna,

I take it you mean “vertebrates,” as in animals with spines (vertebrae are the bones in a spine). Your hypothesis is that lager animals will have more catalase in their livers than smaller ones, although it is not clear whether by “more” you mean more in an absolute sense (grams or moles of catalase total) or in the sense of concentration (grams of catalase per gram of liver tissue). I would say that the former hypothesis is pretty banal, since larger animals have larger livers, which probably have more of pretty much everything than small livers. On the other hand, the latter hypothesis could be interesting to explore. Let’s assume that your hypothesis is that larger animals have a higher concentration of catalase in their livers, measured in milligrams of catalase per gram of liver tissue. Why this might be so, I don’t know, but it gives rise to an interesting experiment at least.

To test for how much catalase is in a fixed weight of each different liver type, I take it you plan to use the oxygen gas evolution test. That should be fine, as long as you can be sure that each liver type was treated in the exact same way. To the best of your ability, each liver sample should be the same age post-mortem, should have the same temperature history post-mortem (all frozen or all not frozen), and the catalase should be released from the cells in each liver sample by the same method as well (some kind of blending procedure followed by cell lysis is probably needed).

That you initially got a result indicating that the fish liver had the most catalase could mean just that, but I can think of a couple of other factors other than leaks that might give the same result even if some other liver actually had a higher concentration of catalase. For example, maybe the cow liver was not cold enough and more of its catalase degraded during storage or transportation. Or, maybe the sheep liver actually had the highest catalase concentration, but it also had the most active proteases, and these chewed up a lot of the catalase during liver storage or transportation.

I would recommend conducting your experiment again with more attention paid to removing as many extraneous, confounding variables as you reasonably can. Such variables are probably mostly related to sample storage and processing. Another thing to keep in mind is that catalases from different animals may have different catalytic activities. Animal A might have lots of a slow catalase, while animal B may have half as much of a catalase that is twice as fast. In your assay, you might obtain a result showing equal amounts of catalase for each animal, even though the situation is quite different. Your oxygen evolution test is really a measure of total catalase activity (catalase amount times catalase activity).

Finally, just in case you didn’t know, MadSci.org has a FAQ page devoted to catalase: http://www.madsci.org/FAQs/catalase.html
Good luck,

Alex Tobias