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How the level of Catechol Oxidase affects the browning on the surface of fruit.

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Introduction

Background research Project title: How the level of Catechol Oxidase affects the browning on the surface of fruit. In order to draw a firm conclusion from the experiment I will be carrying out I need to know exactly what is involved in the experiment e.g. the structure of the enzyme I am using. (1) The enzyme catechol oxidase (7) It is exsists in all plant enzyme and contains a dinuclear copper centre. It is also known as polyphenoloxidase. It catalyses the substrate catechol - O.quinone is then produced. O.quinine reacts with oxygen, Melenine is then formed from the o.quinine reacting with oxygen which are brown compounds are formed from this reaction. (9) Plant cells have a large, fluid filled space in the centre this is known as a vacuole. ...read more.

Middle

(3) The pigment melanin has an important function in both human skin pigment and plants. It Protects from UV radiation as it absorbs the harmful rays. The Black/brown colour means it doesn't allow any energy to escape. Its acts as a protective defence against invading organisms in plants and animals. Melanin is a water-insoluble polymer of various compounds derived from the amino acid tyrosine. It is one of two pigments found in a banana and adds brown to skin color; the other pigment is carotene, which contributes yellow coloring. The synthesis of melanin reactions is catalyzed by the enzyme tyrosinase; an inherited lack of tyrosinase activity results in one of the forms of albinism. Tyrosinase is found in only one specialized type of cell, the melanocyte, and in this cell melanin is found in membrane-bound bodies called melanosomes. ...read more.

Conclusion

(2) The enzyme catechol oxidase and the substrate Catechol will bind to form an enzyme substrate complex. As with all enzymes the activity of Cathechol Oxidase depends very much on temperature, they work slowly at a low temperature and can also be denatured at high temperatures. pH also effects the arte at which the enzymes work. Both these factors would change the enzymes 3 dimensional shape. Enzymes can also be inhibited by substances such as metals. Substrate and enzyme concentration effects the rate of reaction of experiments involving enzymes. (6)Determining the levels of substrates and enzyme and the dynamics of natural enzymic browning as affected by cultivar, physiological age and environmental factors such as temperature. Both potatoes and apples exhibit lowest browning rates at harvest. In apples, the rate increases during storage; however, in potatoes the rate was lower after 6 months storage. Emma Phillips ...read more.

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