Without any further ado, I have a problem concerning my lab experiment. The research question about the topic of enzymes with which I came up (the shortened version of it is the title) is the one that I found the most amusing and interesting. So I went for it. I predicted the activity to go down as the electronegativity of the metal that is in the cation of a salt increased, thus, it becoming less active.
Perhaps I acted too hastily and was not faltered by the almost complete lack of information about this specifically. The only thing was the obvious heavy metal inhibition, but I found some articles claiming that other metals, too, can decrease the activity.
The experiment consisted of me measuring the gas pressure after a time interval when a reaction of peroxide and catalase took place. The more active, the bigger the gas pressure. For different set of trials (I also made a set of trials without any salts) I decided to add different sulphates - sodium, aluminium, iron (II) ... - and that's where the trouble that got me in a bind started. The gas pressure was descending from the set of trials of no salt added, to sodium sulphate, to aluminium sulphate according to the increasing electronegativity of the metals that are in the cations. Looked quite remarkable. But the gas pressure of the iron (II) sulphate was higher than that [/pre][/pre][/pre]of the aluminium sulphate which, considering the last occurrences, should not be the case since iron is less active than aluminium. That was also the point when I started to grow short of the potato juice that I used for the experiment, so I had to terminate it for a while and leave out the proceeding copper (II) sulphate about which I am 100% certain in this experiment of being a total inhibitor.. A buffer solution of 7 pH was used (0.7 ml always) to exclude any shifts of pH when peroxide (3%) was added to the catalase with the salt solutions, the volume - always the same (0.3 ml). Molarities of the solutions were the same (0.2 M), so were the volumes (0.3 ml). The volume of the potato juice was always 2 ml.
So I have a question. Is this experiment even worth continuing since there is a deviation from the prediction and because of the informational shortage in effect of which I am unsure of its fruitfulness? And if it is, why was the occurrence of the iron showing a larger gas pressure than aluminium when iron is less active than aluminium?
My gratitude in advance!
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