Explanations of variations in errors with regards to enzymes

[faisal]

Hello,
how can large variation between sets of different Ph results be scientifically explained, i am investigating the effects of Ph on enzyme activity, there are small error bars in my results between ph1,2,3,4 &5 however there is larger error bars between ph-6,7,8,9 & 10. there's an increase in the rate of reaction from ph-5 to ph-7 after which there is a fall in the volume of oxygen gas released, i have already proposed 3 explanations
-concentration of hydrogen ions higher from the ph-1 to ph3 ranges altered the charge on the R group of the enzyme
-enzymes may have acclimatised readily in ph buffer
-inaccuracy in taking meassurements?

 

[iansmith]

when you graph your results does it look like this graph
http://www.bbc.co.uk/schools/gcsebitesize/img/gcsechem_18part1.gif

-concentration of hydrogen ions higher from the ph-1 to ph3 ranges altered the charge on the R group of the enzyme

Have your consider what would happen at higher pH (8 and up)? What happen to amine and carboxyl functional group at different pH?

 

[DocToxyn]

How many observations are you basing these error bars on? One would predict that they would be rather tight outside the optimum pH range of enzyme activity because the enzyme is not functional there and no activity is no activity. As one approaches the favorable range the enzymes become active and normal variance will be observed. Perhaps it's the low variance in the low pH range that is disturbing you, but I think this is a common observation and perhaps you could reduce the variance in your favorable pH values by taking more observations.