Apparatus-
-A piece of exposed and developed photographic film, big enough to be able to cut twelve equal pieces from it.
-Twelve test tubes.
-A test tube rack, two, if they hold six tubes each.
-A pen, with stickers, to label each test tube.
-A stop clock, to time your experiment.
-5% Savinase standard solution.
-Pipettes.
-A pH9 buffer.
-A water bath, at 40°C.
-And lastly, a thermometer, to make sure the water bath is at a constant temperature.
Method- Label the twelve test tubes 0-5, so there will be two test tubes sharing each number. Pipette 0ml of Savinase into the test tubes labelled ‘0’, and 5ml of buffer into them. Pipette 1ml of Savinase and 4ml of buffer into the test tubes labelled ‘1’. Continue this, finishing at test tubes labelled ‘5’, where 5ml of Savinase is added, with no buffer. Cut the photographic film into twelve equally sized strips, short and narrow enough so that they will be submerged in mixture and that they will fit in the test tube.
Ideally, six test tubes should in one test tube rack, the other six (a repeat test) in another. Put both of the racks into the 40°C water bath (do not submerge the test tubes, just bath them over the level of mixture in the tubes) and time five minutes on the stop clock, so the mixtures in the test tubes should rise in temperature (to 40°C). After the five minutes have passed, add one strip of film into each test tube, try to do this quickly, so that each strip has been in just as long as each other.
Reset and start the stop clock again, and go back to the test tubes. Gently agitate each test tube (can be easier with a partner, so each test tube is tendered to at the same time) or test tube rack, since Savinase is not powerful enough to separate the protein from the film completely.
After time, you will notice that in some beakers, the reaction will have finished, and you can tell this by the liquid appearing as a dark grey colour (due to the silver being released from the film) and that the film is now completely transparent, clear, and colourless. Record the time that each finished reaction occurs at.
Results-
Notice that for 0% Savinase the time was 0 seconds, this was not the case, as it would have been ∞, since it would never react (due to there being no Savinase present), so in my graph I put this value as 0, just to include it.
Evaluation- The experiment went quite well in my mind, and was carried out accurately. If I was to change a few things, one would be to have some sort of ‘Agitation Machine’, so that each of the test tubes could be agitated equally, since if one is agitated a lot more than another, the protein may come apart earlier than it should, and one may have separated slower, due to it not being agitated enough. Another thing I would change is the method of inserting the film strips, since they are inserted at slightly different times, and this will lead to error. To fix this I would insert each one at ten or thirty second intervals, and then work out the difference in time relative to the others.
Conclusion- From this experiment I can deduce that the concentration of an enzyme does effect the time the reaction takes, and the lower the concentration, the slower the reaction takes to complete. The higher the concentration, the faster the reaction takes to complete, but up to a point (where there are the same amount of particles to react and enzymes) the reaction will not take any less time, since the enzymes will react with one particle each, and this is the fastest situation, the extra amount of enzymes will be useless.
