Investigating the Properties of the Enzyme Catalas Essay

This essay has a total of 1670 words and 35 pages.

Investigating the Properties of the Enzyme Catalase


Introduction


The discovery of enzymes occurred accidentally in the late nineteenth century. The German
chemist Eduard Buchnar had been attempting to harvest fluid derived from yeast extracts,
to his exasperation the fluid extracts taken kept decaying. With the knowledge sugar acts
as a preservative of fruit, Buchnar introduced sugar to his liquid extracts in the hope
the sugar would preserve the yeast extracts. To his astonishment the yeast fluid
dissolved the sugar resulting in fermentation, producing alcohol. Twenty years prior to
Buchnarís findings Louis Pasteur had already established fermentation could be achieved by
using yeast. Pasteur believed the living yeast cells caused the fermentation to take
place. As Buchnarís findings show the fluid from the yeast was in fact responsible.



Enzymes are globular (complex three dimensional) proteins which consist of polypeptide
chains joined together. They are responsible for all the biochemical reactions in the
body. Divided into two groups, extracellular (produced inside the cell, used outside the
cell i.e. digestive enzymes (pepsin) break down food in the gut) and intracellular (used
to speed up and control metabolism (ATPase) inside the cell). Enzymes act as catalysts,
(substances that speed up the rate of a chemical reaction by reducing the activation
energy necessary to initiate the reaction, without changing the enzymeís properties).
Enzymes do not make fresh reactions occur; they only balance an ongoing reaction at a
safer and lower temperature (at the same rate as the living organisms in the body).
Enzymes provide an active site (a three-dimensional structure which only admits a relevant
substrate) described as working on a lock and key basis. (This basically means if the
substrate is the right shape and correct biological property it can bind with the enzymes
active site).



There are a number of factors that can either aid (activator) or hinder (inhibitor) the
reaction rate of an enzyme. An activator interacts with the enzyme and increases its
activity, whereas an inhibitor binds with the enzyme to decrease its activity.



The experiment to be carried out focuses on the enzyme Catalase. Located in the
peroxisome (cell organelle responsible for the oxidation of fatty acids and synthesis of
cholesterol and bile acids). The substrate to be used (Hydrogen Peroxide) is a product
produced by the oxidation of fatty acid and also produced by phagocytes in white blood
cells (to kill bacteria). Catalase has the ability to spilt hydrogen peroxide into water
and oxygen. The purpose of the experiment is to investigate the properties of catalase.



Method


Before the experiment can be performed the following safety precautions should be observed:


v Laboratory coat must be worn to avoid spillage of corrosive substances on skin and clothes.


v


v Eye protection must be worn to avoid substances coming into contact with eyes.


v The location of the eye station (medical eye wash kit) should be noted in case of
substances coming into contact with the eyes.



v If H2O2 is spilt onto the skin rinse under water immediately. Inform person regulating the experiment.


v When handling the liver follow basic kitchen rules, (use chopping board, wash hands
after contact, all waste liver in the bin).



v To enable safe discard of waste liquid substances, the experiment should be performed next to a sink.


Stage 1


The following equipment is required:


v Cutting board


v Scalpel to cut liver


v Tweezers to handle liver


v 1ml syringe for teepol


v 5ml syringe for H2O (distilled water)


v Syringe for H2O2


v Time piece (stopwatch)


v Measuring cylinder.


v 9 equal portions of liver


v 27ml of H2O2 (20 vols) Hydrogen Peroxide


v 9ml of teepol


v 48mls of H2O (water)


1ML TEEPOL


4ML H2O2 (20 VOLS)


LIVER (1CM3)


4ML H2O


TEST 1


#


#


#


#


TEST 2


#


#


#


TEST 3


#


#


#


TEST 4


#


#


#


EACH TEST NEEDS TO BE REPEATED 3 TIMES TO OBTAIN AN AVERAGE.


Stage 2


Once the safety rules have been observed and all equipment gathered the experiment can commence.


The ingredients need to be added in the correct order shown in the table above, i.e. for
test 1 add the teepol first, H2O2 second, liver third and lastly add H2O.



As soon as all the ingredients have been added to the cylinder start the time piece.
After 30 seconds has passed measure the amount of foam in the cylinder, repeat this
process every 30 seconds until the foam measures the same on three consecutive times.
Record answers, and then repeat each test twice to achieve an average.



Results


Test 1


TIME (SECONDS)


TEST A


TEST B


TEST C


AVERAGE


30


12cm3


14cm3


20cm3


15.3cm3


60


14cm3


17cm3


24cm3


18.3cm3


90


15cm3


20cm3


26cm3


20.3cm3


120


17cm3


22cm3


28cm3


22.3cm3


150


20cm3


24cm3


30cm3


24.6cm3


180


21cm3


26cm3


32cm3


26.3cm3


210


23cm3


29cm3


35cm3


29.0cm3


240


24cm3


30cm3


36cm3


30.0cm3


270


26cm3


32cm3


37cm3


31.6cm3


300


26cm3


32cm3


37cm3


31.6cm3
Continues for 18 more pages >>




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