Investigating Enzymes Essay Research Paper Research Enzymesexist

Investigating Enzymes Essay, Research Paper

Research Enzymes

exist in all living things. They are composed of polymers of amino acids and

are produced in living cells. Each cell contains several hundred enzymes, which

catalyse a vast number of chemical reactions. Enzymes are known as Biological

Catalysts as they dramatically increase the rate at which reactions occur

within living organisms, without being .used up. or effecting the reaction in

any other way. Enzymes catalysis saves the need for an increase in temperature

in order to speed up reactions within living things. Such an increase in

temperature would be lethal to the organism. In

this investigation I intend to explore the one of the factors that effect the

rate of enzyme catalysis. My research from textbooks and the Internet suggests

that this depends on several factors; temperature, pressure, pH and

concentration. After research and careful consideration, I have decided to

first look at how a change in temperature could affect the rate of reaction. In

order to design a suitable experiment and make a credible prediction, I must

first explore more closely how temperature is likely to affect the rate of

catalysis. Enzymes are specific – they only control one type of reaction;

therefore I must use one specific enzyme in my experiment, in order to find a

clear way of measuring the rate of reaction. Although they are specific, all

enzymes work in a very similar way and have similar properties. They are all

globular proteins and are all biological catalysts, they increase the rate of a

given reaction without being used up and their presence does not change the

nature of the reaction or the end product. Enzymes work by having an active

site, made from amino acids. Here, substrate molecules will bind with the

enzyme (and other substrate molecules if necessary) and a reaction takes place.

The enzyme itself is not affected and releases the new chemical after the

reaction. After release of the end product, more substrate molecules can bind

with the active site. Enzymes

can catalyse anabolic reactions or catabolic reactions (involved in breakdown).

The diagram above shows an anabolic reaction. In a catabolic reaction, the reverse

would happen. Using

the information gained here together with my knowledge of kinetic theory, it is

possible to understand how temperature affects the rate of reaction. Kinetic

theory states that when a substance is heated, energy is given to the particles

and they speed up. Therefore when heat is applied to an enzyme and substrate,

the particles speed up, increasing the rate at which they bind with each other.

This would suggest that the rate of reaction should increase as the temperature

is increased. This is not quite true, as there is a limit to the temperature at

which an enzyme can work because excessive heat causes an enzyme to become

denatured and stop working. Also, there is a minimum temperature at which an

enzyme can function. Every chemical reaction requires activation energy in

order to get started. Although enzyme catalysis greatly reduces this, some

energy is still required. Because of this the reaction is still unable to

happen below a given temperature (this varies depending on the type of enzyme

and reaction, as does the maximum temperature). If warmed to above the

activation temperature, an enzyme will work again as normal. A denatured

enzyme, however, is damaged and will not work again even if cooled below the

optimum temperature. Prediction I

predict that the rate of reaction will increase as the temperature increases

until the reaction reaches an optimum temperature. Above this optimum

temperature, the rate of reaction will fall to zero very quickly, as the enzyme

denatures. I must now conduct an experiment to test my prediction. I will do

this using the enzyme catalyse. Catalyse is found in most living organisms. It

speeds up the catabolic reaction, which breaks down hydrogen peroxide into

oxygen and water. Apparatus Using

my information on catalyse, it is clear that one of the products of the

reaction is oxygen. Therefore to measure the rate of reaction, I could measure

the rate at which oxygen is produced. For this experiment I will need: Leek

as the source of catalyse Hydrogen

peroxide A

water bath in which I can heat both enzymes and substrate Thermometers

to ensure both liquids are at the correct temperature Measuring

cylinders in order to measure the amount of oxygen produced, as well as

the amount of yeast/hydrogen peroxide used A

timer to enable me to work out the rate at which oxygen is produced A

basin of water Conical

flask in which the reaction will take place Bung

and delivery tube Method To

test my prediction I will heat the catalyse and hydrogen peroxide to a given

temperature and allow them to re

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