An Investigation Into The Digestion Of Milk By Trypsin.

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Mehul Patel UVB

An Investigation Into The Digestion Of Milk By Trypsin

Background Knowledge

A protein called casein produces the opaque colour of milk, enzymes can be used to digest the milk and therefore make it translucent.  When milk is digested by trypsin and , a fat-digesting enzyme that also originates in the pancreas and that shows the same clinical variations as amylase in disorders involving the pancreas.

Enzymes are proteins that act as biological catalysts. They are made up in the cells. A catalyst is a chemical substance, which speeds up a reaction but does not get used up during the reaction. One enzyme can be used as many times over. There are two types of enzyme reaction; the first is ‘Anabolic’ reaction- this is when large molecules are built up from smaller molecules. The second type of reaction is called ‘Catabolic’ reaction- this is when large molecules are broken down into smaller ones.

Temperature effect on enzymes:

Enzymes work at an optimum temperature of 40-50°c as the enzyme produces just the right amount of kinetic energy. A rise in temperature increases the rate of most chemical reactions; a fall in temperature slows them down. In many cases a rise of 10°c will double the rate of reactions in a cell. This is equally true for enzyme-controlled reactions, but above 50°c the enzymes, being proteins, are denatured and stopped working.

Above 50°c the shapes of enzymes are changed and cannot therefore combine (lock and key theory) with the substance.

 

This is one reason why organisms maybe killed by prolonged exposure to high temperatures. The enzymes in their cells are denatured and the chemical reactions happen too slowly to maintain life.

One way to test to see if a substance is an enzyme is to heat it to boiling point. This is used as a control in enzymes experiments.

Enzymes function most efficiently within a physiological temperature range. Since enzymes are protein molecules, high temperatures can destroy them. An example of such destruction, called protein , is the curdling of milk when it is boiled. Increasing temperature has two effects on an enzyme. First, the velocity of the reaction increases somewhat, because the rate of chemical reactions tends to increase with temperature; second, the enzyme is increasingly denatured. Increasing temperature thus increases the metabolic rate only within a limited range. If the temperature becomes too high, enzyme denaturising destroys life. Low temperatures also change the shapes of enzymes. With enzymes that are cold sensitive, the change causes loss of activity. Both excessive cold and heat are therefore damaging to enzymes.

pH effect on enzymes

The degree of acidity of a solution, which is expressed as pH, also affects enzymes. As the acidity of a solution changes--i.e. The pH is altered--a point of optimum acidity occurs, at which the enzyme acts most efficiently. Although this pH optimum varies with temperature and is influenced by other constituents of the solution containing the enzyme, it is a characteristic property of enzymes. Because enzymes are sensitive to changes in acidity, most living systems are highly buffered; i.e., they have mechanisms that enable them to maintain a constant acidity. This acidity level, or pH, is about 7 in most organisms. Some bacteria function under moderately acidic or basic conditions; and the digestive enzyme pepsin acts in the acid milieu of the stomach. There is no known organism that can survive in either a very acidic or a very basic environment.

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Acid or alkaline solutions alter the chemical properties of proteins, which includes enzyme. Most enzymes work best at a certain level of acidity or alkaline (pH). The protein digesting enzymes in your stomach of example, they work best at pH of 2. At this pH, the enzyme amylase, from your saliva cannot work at all. Inside most cells the enzymes work best at a pH of 7, as it is neutral. The pH or temperature at which this enzyme works is called its optimum pH or temperature.

Although changes in pH affect the activity of enzymes, these effects are ...

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