Effect of Temperature on Activity of Alcalase and Savinase

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  • Topic: Enzyme, Protease, Laboratory glassware
  • Pages : 5 (1638 words )
  • Download(s) : 2422
  • Published : August 30, 2008
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Hypothesis
The optimum temperatures of Alcalase and Savinase will be different. Above and below their optimum temperatures activity will decrease.

Biological explanation
This investigation is designed to look at the effect of temperature on the activity of the proteases Alcalase and Savinase. By the end of it I hope to know the optimum temperature of both proteases.

The substrate I am going to use during the experiments is the protein gelatin, which is a translucent, colourless, brittle solid substance found in the collagen inside an animals’ connective tissues. In my experiments it is going to be in the form of a single, thin layer, used on the surface of photographic film. It is useful in photography because it acts as protein glue, sticking the silver halide crystals to the surface of the plastic film. I am using it in this form, as it is easy to see when the enzyme has digested the gelatin. This is because normally the surface of the gelatine-silver halide layer turns black when exposed to light. However, when the enzyme has removed the gelatin the black colouring will disappear and only the clear plastic will be visible. Therefore, it can be easily identified when the reaction between the enzyme and the gelatin is complete, so this form of gelatin is very appropriate.

Alcalase is a high temperature protease, meaning it works best at high temperatures, so its optimum temperature must be fairly high in relative terms, taking into account that most biological enzymes have an optimum temperature of 37.5°C. It is commonly found in soil. Due to it being a high temperature protease I would expect its activity to increase with the temperature up to its optimum temperature, which I think may be about 50°C. I predict its optimum temperature to be around this figure because the enzyme is used in washing powders and this is a reasonable temperature to washing clothes at.

Savinase is a low temperature protease, meaning it works best at low temperatures, so its optimum temperature must be fairly low in relative terms, taking into account that most biological enzymes have an optimum temperature of 37.5°C. It also is found in soil. Due to it being a low temperature protease I would expect its activity to decrease as the temperature increases once the temperature is above its optimum temperature. I think the optimum temperature will be about 30°C because this enzyme is also used in washing powder, but in special energy saving washing powder, which operates at 30°C. The proteases are able to break down the protein gelatin because they are specific to the reaction needing to take place. They are specific in that their active sites on the surface of the enzyme fit the gelatin substrate, fulfilling the lock and key hypothesis and forming an enzyme-substrate complex. The optimum temperature is the temperature at which these formations occur most efficiently, due to the enzymes active site being the most accurate shape to fit the substrate. Therefore, temperature affects the activity of enzymes by changing the shape of the active site, which means it is changing the tertiary structure of the enzyme. The tertiary structure is changed because the weak hydrogen bonds that hold the protein in its 3D helical shape are broken due to the heat. As well as the enzymes active site being the correct shape at the optimum temperature there is a better balance of kinetic energy, causing more collisions between enzyme and substrate and therefore more enzyme-substrate complexes are formed, increasing activity. At high temperatures in comparison with the optimum temperature the enzymes tertiary structure may change completely, disabling all activity, as the substrate won’t fit the active site. This is known as denaturation. However, at temperatures below the optimum, the tertiary structure of the enzyme isn’t altered and denaturation does not occur, it is simply a slower rate of reaction due to less kinetic energy and therefore reduced...
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