Investigation On The Enzyme Trypsin
Investigation On The Enzyme Trypsin
An Investigation determining a factor affecting the rate of digestion of gelatin by the protease trypsin.
Introduction
An enzyme is a biological catalyst, which speeds up reactions. An example of this in the human body is trypsin (a protease produced in the pancreas and used in the stomach), which catalyses the digestion of gelatine, a protein. For this investigation, a photographic film will be the source of the gelatine. I will be able to identify when the gelatine is digested, when the photographic film turns from a dark brown colour, to being transparent.
All enzymes are proteins, which are specific to the molecule that they break down. This is known as the ‘lock and key’ theory, where the active site only allows a specific substrate to be broken down, eventually resulting in easier absorption (larger surface area). Enzymes are made up of a long chain of amino acids, which form together in such a way as to leave a specific pocket, into which a substrate (as long as it fits perfectly into the pocket) can fit into it like a key in a lock (hence the ‘lock and key’ theory). The reaction then takes place, and the product of the substrate is then released. The enzyme, not changed by the reaction, can then perform the same “operation” on countless other substrates.
Because the enzyme can be re-used, only a small amount is needed. Despite this enzymes can make cell reactions go many million times faster than they would normally. Since enzymes are biological catalysts, by definition, they are not used up or changed in the reaction that they catalyse. Even though they cannot be used up, when subjected to a high temperature (50°C and above), enzymes can become denatured and the active site damaged or destroyed. After denaturisation, the enzyme becomes useless as no more substrates can become further digested by them.
Since there was ample trypsin for our use, and because trypsin begins to denature by 50°C (the temperature of the water bath I was using), I used a fresh batch of trypsin for each experiment I performed.
Before I started, it was important for me to decide what factor I was going to set as my independent variable and what I was going to setting as my dependant variable. There were several possibilities. Since speeding up the reaction was obviously one option, I...