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The effects of temperature, PH value, substrate & enzyme concentration and those of inhibitors and cofactors are of particular biological interest and can be summarized as follows:-

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Enzymes are globular proteins and within the cell they have two fundamental roles: > They act as highly specific catalysts, greatly speeding up chemical reactions which would otherwise be hopelessly slow > They provide a mechanism whereby individual chemical reactions can be controlled, the available quantity of an enzyme determine the rate of the corresponding reaction. At the moment, hundreds of chemical reactions are in progress in a typical living cell. Theses reactions provide energy and help to maintain supplies of the many different substances needed for growth & repair. The remarkable fact that all these reactions contribute to an organized overall metabolism is due almost entirely to the production of special substances called enzymes. You can see from the fig that the specificity of an enzyme's action arises because each enzyme has a definite three dimensional shape which is complementary to that of its reacting molecules, or substrates. The first step in any reaction catalyzed by an enzyme is the formation of a specific association between the molecules called an enzyme-substrate complex. This is made possible by the fact that the configuration of the enzyme matches the shape of the substrate over a relatively large area called active center of the enzyme. ...read more.


At the other extreme, the ice fish of Antarctic waters has enzymes which function efficiently at -2�C. Most enzymes have an optimum pH close to pH 7, which is the normal intracellular pH. This is illustrated in the figure. Enzymes which work extra cellularly can have very different pH requirements. A notable example is the enzyme pepsin which is found in the stomach and works best in highly acidic conditions in the range pH 1 - 2 pH changes away from the optimum can affect enzyme activity adversely in either of two ways. In cases where the binding or catalytic sites within the active centre take the form of charged ions, some values of pH are inhibitory because they cause these ions to re associate. The uncharged groups formed as a result can no longer interact with the substrate & so catalytic activity is lost. A second possibility is that the enzyme molecule can change shape and become denatured: this is more likely to happen at extreme values of pH which tend to weaken the forces holding the enzyme molecule together. In my course work, I am investigating the effect of temperature on the activity of enzymes. ...read more.


prepare a syringe full of hot water so as the temperature goes down we can add water from the syringe to maintain constant temperature needed for fair comparison. We could use sensitive balance to measure the mass of the potato discs used in the experiments so we can have more accurate results needed for fair comparison. Using suitable length of the connecting tube so as not to have a lot of air inside it which would affect the accuracy of the experiment & also a suitable size of a measuring cylinder so as we can see the small differences I think that further investigation is needed to use wider range of temperatures and more accurate equipments to obtain more accurate results. : It is obvious that there were sum errors in my experiments as on using temperature 20�C as more oxygen was released more than predicted & I think that was because of the air inside the tube as heated and expanded & made more air released. I think that some oxygen was lost in the time between putting the hydrogen peroxide & closing the stopper over the test tube. But I think that I did my best to have the most accurate results I could obtain. ?? ?? ?? ?? ...read more.

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