Enzyme Lab Report

Divya Aishwarya Gandi

Enzyme lab report Research Question:

How does increasing the concentration of the substrate, in this case, hydrogen peroxide (0.75%, 1.50%, 3.00%, 4.50%, and .00%! affect the rate of en"y#e acti$ity of cataase obtained fro# potato tissue, on deco#posing the hydrogen peroxide& Background Information:

'n"y#es are bioogica cataysts that catayses bioche#ica reactions in i$ing ces. n an en"y#e)cataysed reaction, the substrate binds to the acti$e site and for#s en"y#e)substrate co#pex with the en"y#e. *he en"y#e then brea+s the bonds in the substrate. *he product of the reaction then ea$es the en"y#e, which re#ains unchanged after the reaction. ataase in an en"y#e produced by our i$er to brea+ down hydrogen peroxide - a co##on end product of #etabois#, but highy toxic if accu#uated in the body - into water and oxygen. *he euation of the reaction is as foows/  H

 2  H ataase

hen cataase is added to hydrogen peroxide, there is an initia rapid e$oution of oxygen which asts for about two #inutes, depending on the peroxide concentration. fter this, oxygen is gi$en off at a steady rate which sowy decreases in the course of an hour. *his decrease in the rate is undoubtedy due to en"y#e destruction. *he rapid e$oution and the steady steady rate, rate, howe howe$e $er, r, are inhe inheren rentt featu feature ress of the the pero peroxi xide de deco deco#p #pos ositi ition on.. 1n this this experi#ent, we obtain hydrogen peroxide soution and extract cataase fro# potato. iter paper discs are dipped into the cataase soution before they are sub#erged in hydrogen peroxide soution. *he oxygen produced fro# the en"y#e reaction wi for# on the disc s and caus causee the the disc disc to be buoy buoyan antt enou enough gh to foat foat upwa upward rds. s. *hro *hroug ugh h this this #eth #ethod od we can in$estigate the effects of substrate concentration on the rate of reaction. e #anipuate the substrate concentration by using different concentrations of hydrogen peroxide soution, and #easure the rate of reaction by #easuring ti#e ta+en for enough oxygen to be produced so that the disc to foat to the surface.

Hypothesis:

*he ti#e ta+en for the cataase to brea+ down the hydrogen peroxide wi decrease as the concentration of the substrate increases, pro$ided that a other externa factors are +ept constant. *his is because there wi be a greater rate of reaction due to there being #ore coisions and a ower acti$ation energy. Howe$er, after a certain point there wi not be an increase in the rate of reaction as the en"y#e concentration beco#es the i#iting factor.

1 http://www.nature.com/nature/jour http://www.nature.com/nature/journal/v160/n4054/as/160041a0.html nal/v160/n4054/as/160041a0.html


Variables:

Independent "ependent

#ontrolled

Variable oncentration of the hydrogen peroxide. *i#e ta+en for the fiter paper to rise to the top of the soution. *e#perature

*ype of tissue

'n"y#e concentration

9ou#e of hydrogen peroxide

8i"e of the test tubes

:ia#eter of the fiter paper.

Value(s 0.75%, 1.50%, 3.00%, 4.50%, .00% n seconds (s!

6oo# te#perature (!

!ustification

n order to deter#ine the rate of en"y#atic reaction.

'n"y#e reactions are affected by externa te#perature, hence the te#perature is +ept constant so that the ony factor affecting the rate of reaction is the substrate concentration. 8a#e potato used *o ensure that the sa#e concentration of en"y#e is obtained. 1 fiter paper soa+ed *his is to ensure that ony the in the potato soution. substrate concentration is affecting the rate of reaction. *he crushing of a singe potato ensures that there is a ho#ogenous potato soution, which #eans that the concentration of cataase is constant throughout. 3 7.5 c# *his ensures that the sa#e nu#ber of hydrogen peroxide #oecues is a$aiabe for the reaction e$en though they $ary in concentration. 8a#e width and *his is to ensure that the ength distance that the fiter paper disc has to tra$e is the sa#e. *a+en fro# the sa#e *his is so that the cataase dis+. pprox 0.5 ## absorbed is of the sa#e uantity and so that the oxygen reuired to ift it, is the sa#e during each tria.


$aterials and %pparatus: •

:igita stop watch, accurate to 0.01 s (x1! &ncertainty: ')*

•

*est tubes (x!

•

*est tube hoder (x1!

•

;ass 6od

•

'ectric bender

•

•

=nife

• •

>este and ?ortar 8ie$e

•

>etri dish

•

*wee"ers

•

>ipette (dropper! (x1! &ncertainty: '),cm +

•

% hydrogen peroxide soution

•

>otato (x1!

•

iter paper dis+s

•

:istied water


-rocedure.:

1. 0.75 % hydrogen peroxide soution is prepared by #easuring 3.00 c# 3 of  % hydrogen peroxide using a #easuring cyinder and then diuting it with 1.00 c# 3 of distied water. 1.50 %, 3.00 %, 4.50 % and .00 % hydrogen peroxide soutions are prepared using the sa#e #ethod the with corresponding $ou#es of  % hydrogen peroxide and water as shown in the tabe beow

oncentration of hydrogen peroxide soution @% (A 0.0!

9ou#e of  % hydrogen peroxide @ c#3 (A 0.01!

9ou#e of water added @ c#3 (A 0.01!

0.75 3.00 1.00 1.50 .00 1B.00 3.00 1.00 1.00 4.50 1B.00 .00 .00 4.00 0.00 *abe 1/ :iution tabe for preparing different concentrations of hydrogen peroxide soutions *he prepared hydrogen peroxide soutions are poured into test tubes using pipettes. 'ach test tube shoud contain 7.5 c# 3 of the soution. *he test tubes with their soutions are paced in the test tube hoder, abeed and set aside as stoc+s. .  potato is peeed and cut into cubes. *he potato cubes are then ho#ogeni"ed by crushing the# in water. *he crushed potato is fitered using sie$e and the fitered iuid is coected in a bea+er. 8o#e of the fitered potato iuid is put into a >etr i dish to be used in the experi#ent. 3.  fiter paper disc is soa+ed with potato iuid in the >etri dish and pushed to the botto# of a test tube with 0.75 % hydrogen peroxide soution using a gass rod. 4. *he stopwatch is started i##ediatey when the fiter paper disc touches the botto# of the test tube. 5. *he stop watch is stopped once the fiter paper disc reaches the surface. *he ti#e ta+en for the fiter paper disc to foat to the surface is recorded. . 8teps 3 - 5 are repeated twice, using other new 0.75 % hydrogen peroxide soutions. 7. *he a$erage of the 3 readings for each hydrogen peroxide concentration is cacuated and recorded. *he rate of reaction is cacuated by the foowing for#ua/ 6ate of reaction C B. 8teps 3 - 7 are repeated 5 ti#es with 1.50 %, 3.00 %, 4.50 % and .00 % hydrogen peroxide soutions. ! http://www.slideshare.net/w""o"1#5$/i%iolo&y%on%decomposition%o'% hydro&en%pero(ide%y%en)yme%catalase


/afety -recautions:

1. . 3. 4.

Hydrogen peroxide is corrosi$e so wear atex go$es whie handing the soutions. Hande a gass apparatusD with care. Hande +nife and scape with care. 'xercise caution whie using the eectric bender. $oid paraax error whie #easuring the $ou#e of soutions by pacing eye perpendicuar to the ower #eniscus

Ra0 data 1able sho0ing the amount of time taken for the filter paper disks soaked in catalase to reach the surface of the test tube:

oncentratio n of hydrogen peroxide soution@ % (A0.0! 0.75 1.50 3.00 4.50 .00

*i#e ta+en for the fiter paper dis+ to reach the surface@s (A0.1!

*ria 1 1E.E 11.0 10.75 10.00 7.41

*ria  0.75 10.7 11.E0 10.00 7.3

*ria 3 3.1 11.53 11.1 10.7 .00

*ria 4 1.3 11.1 11.13 E.B1 .3

*ria 5 0.15 10.BE 11.75 10.3 .71

-rocessed data table sho0ing the a2erage time taken for the filter paper to reach the surface of the test tube for each concentration of hydrogen pero3ide:

oncentratio n of hydrogen peroxide soution@ % (A0.0!

0.75 1.50 3.00 4.50 .00 &ncertainties:

*i#e ta+en for the fiter paper dis+ to reach the surface@s (A0.1! 1.01 11.1E 11.34 10.17 .B0

6ate of reaction@s) 1

0.04B 0.0BE 0.0BB 0.0EB 0.147

Fncertainty in concentration of hydrogen peroxide/ A0.0


Fncertainty in ti#e ta+en for fiter paper dis+ to reach surface/ 0.01 2 0.C A0.1 (here A0.01 is due to the stopwatch and A0. is due to the hu#an reaction ti#e! >ercentage uncertainty in ti#e ta+en for the fiter paper dis+ to reach the surface@% cacuated using/

Average timetaken for t h e filter paper 0.21

¿

reac h t h e surface ¿ × 100

Absolute uncertainty for rate of reactionrat e of reaction× percentageuncertainty

oncentration of hydrogen peroxide soution@ % (A0.0! 0.75 1.50 3.00 4.50 .00

$erage ti#e ta+en for the fiter paper to reach the surface@s (A0.1! 1.01 11.1E 11.34 10.17 .B0

>ercentage uncertainty in ti#e ta+en for the fiter paper dis+ to reach the surface@% 0.EE 1.B7 1.B5 .0 3.0E

∈time taken

bsoute uncertainty in rate of reaction

6ate of reaction with uncertainty@s)1

0.475 0.1 0.1 0.0 0.454

0.04B A 0.475 0.0BE A 0.1 0.0BB A 0.1 0.0EB A 0.0 0.147 A 0.454

Qualitati2e data:

*here was i##ediate for#ation of bubbes when the fiter paper soa+ed in cataase was added to the hydrogen peroxide. *his is because of the for#ation of oxygen which pushes the fiter paper up to the surface.

4raph sho0ing the concentration of hydrogen pero3ide56 ('). against the rate of reaction5s 7*(').*


%nalysis of graph:

*he graph shows a steady increase in the rate of reaction unti the concentration reaches 3.00% where there is a s#a drop of 0.001s )1, this ano#ay can be said to be on account of hu#an error, either whie preparing the soution or whie ti#ing the fiter paperDs rise to the surface. fter this the rate of reaction continues to increase steadiy. Howe$er, in genera the trend of the graph shows that as the concentration of the substrate (hydrogen peroxide! increases so does the rate of reaction. *here are arge error bars for the rate of reaction which shows that the experi#ent was not $ery accurate. *his is due to hu#an error and hu#an reaction ti#e whie ta+ing the ti#e. #onclusion:

ro# the data coected and the trend of the graph, a positi$e correation can be seen with an increase in the rate of reaction as the substrate concentration increases. *his pro$es #y hypothesis to be right athough the concentration of the hydrogen peroxide did not increase to the extent to #a+e the cataase concentration the i#iting factor. *his can be expained by the fact that there are #ore substrate #oecues coiding with the en"y#e #oecues pro$iding a greater probabiity for a reaction to ta+e pace and therefore increases the for#ation of the product, in this case the oxygen which pushes the fiter paper to the surface. Howe$er there


is an ano#aous $aue for the 3.00% hydrogen peroxide concentration in which there is a decrease of 0.001s )1. gain this shows that the experi#ent was not $ery accurate. E2aluation: /trengths: •

*he controed $ariabes were +ept constant throughout the experi#ent increasing

•

reiabiity of the resuts obtained. 8e$era trias (5! were conducted to gi$e #ore accurate readings for the ti#e ta+en

•

and therefore the rate of reaction. *he experi#ent was conducted in one session so there was no roo# for spoiing of the potato or change in concentration of the soutions.

8imitations iter paper dis+ was not of the sa#e circu#ference.

Impro2ements Fse a cutter or te#pate to #a+e sure each dis+ is the exact sa#e si"e and circu#ference to reduce error. Fse #ore concentrations of hydrogen peroxide in order to ha$e a arger spread of data and to study the effect in detai.

*here was not a great enough para#eter in the concentrations of hydrogen peroxide which did not aow for the graph to reach a steady point at which the en"y#e concentration woud beco#e the i#iting factor and the substrate concentration woud ha$e no effect.  contro tria was not carried out which  contro tria woud ensure that no oxygen is coud resut in inaccuracies going undetected. being produced and the fiter paper woud not rise aowing there to be a co#parison between the en"y#e cataysed reaction and en"y#e non)cataysed reaction. :isparity in the way the air bubbes are produced which #eant that the rise of the fiter paper was not aways constant. *he fiter paper stic+ing to the was of the

produced. *here coud ha$e been hu#an error in the preparation of the different hydrogen peroxide concentrations which woud ha$e ead to ano#aous readings for an entire concentration.

was. Fsing ready)#ade soutions or preparing the soution for each concentration #ore than once and conducting se$era trias woud #a+e it easier to detect hu#an error and woud aso reduce inaccuracies, #a+ing the data #ore reiabe.

Enzyme Lab Report

Recommend Documents