Module 2.4 Flashcards
1
Q
enzymes increase the rate of reactions ( make reactions fater ) . MEANING ENZYMES ARE CTALSYSTS .
A
aS WE FND ENZYMES IN LVIING ORGANSIMS , WE SAY , ENZYMES ARE bioligcal catalsysts .
2
Q
Check sheet for the equation with hdyrogen perxoide
A
the enzyme is CATALAE .
-as we find catalase inside cells , catalase is an example of an intracellular enzyme .
-Catalase , binds to the toxic moelcule , hydrogen perxodide and speeds up its breakdown to the harmless molecules wter + oxygen .
3
Q
Amyalse , is another enzyme , unlike catalase , amyalse is not found isndie cells .
-Check sheet for equation .
A
…
4
Q
Amylase is pordued in the pancrease and released into the small intenstine .
A
JOB of amylas eis to catalsye the breakdowns trarch moelcules into the disa
5
Q
ccharide maltsoe .
-Maltose is then brokken by other enzymes into glucose .
-Which is abosrbed into the bloodsream .. As we ind amalse outide cells ,w e say that amyalse is an exmaple of an extracellualr enzume .
A
yeah come one ,
6
Q
Another example of an enzyme .
-Check sheet for equation .
A
Trypsin , is another exmpale of an extraceullr enzyme , Trypsin is produced by the pancreas and released into the digestive system .
7
Q
What is the job of trypsin ?
A
To catalyse the breakdwon of protein moelcules , into shorter fragments called peptides .
-Again , other enzymes break down peptides into mino acids , which can be abosrbed into blodstreams .
8
Q
In each of these examples
A
the enzyme attaches to and breaks down another moelcules .
9
Q
What is the substrate
A
(hydorgen peroxide ,s tarch , proteins )
-The moelcule that the enzyme attaches to is called the SUBSTRATE MOELCULE .
10
Q
What is the product ?
A
The moelcules porduces (Water + oxyge , maltose and peptides . )
11
Q
-The vast majority of enzymes are globular proteins .
What are globular proteins again ?
A
Globular porteins have hydrophillic amino cids on their surface and any hydrophobic amino cids are buried within the center of the prtoein .
-Making Globular porteins osluble in water .
12
Q
Check sheet for simplfiied strucuture of enzyme molecule
A
-On the surface of an enzyme moelcule , we find a groove , which scieniststs call the active site .
-The job of the active sitwe is to attach to the substarte moelcule .
-Scienits now call the enzyme substrate complex .
13
Q
Key ; the tertiary strucutre of the active site is complementary too the strucuture of the susbrate
AL , the susbrtae meolcue fits perfectly inot the ctive site .
A
BECAUSE O THIS , each enzyme is specific for the substarte it binds to .
-As youc an see , a molecul with a strucuture different to the substarte cannot successfully bind to the active site .
14
Q
What happens when the substrate bind to ?
A
Oncd the susbtarte binds , the aminoa cids on the suraface of the active site ,c an form temproary bonds witht he susbtrate moelcule .
-The enzyme then catalsyes the reaction . TO FORM the enzyme product compelx .
-now th PRODUCTS ARE RELSED FROMT HE ACTIVE SITE .
15
Q
key ; NEED TO UNDERSTAND is that in any reaction , the moelcules must have a certain amount of energy before they can react .
A
Scienits call this hte ctivationn energy . Anu moelcles , whch don’t hae at leasst the actvation energy CANNOT REACT .
-Enzymes rpodvide a pathway for the ractio with a lower ACTIVATIONE ENEGRY .
16
Q
iN THE PRESENCE OF AN ENZYME
A
tHE ACTIATION ENERGY barrier is lwoer than it would be without the enzyme .
-This means that more subsrat emoielcuels , now have enogiuunenergy tocross the activation energybarrier and react .
-SO THE presecne of an enzyme , the reavtion rate increases .
17
Q
On the surface , the tertiaery strucuture of the enzyme , folds into three dimensional shape called the active site .
A
The active site is a aprt of the enzyme where the substrate molecule attached to form the enzyme substrat ecomplex .
18
Q
As we have seen , the tertiary strucutre of the active site is specific to the strucuture of the substrte moelcule .
A
Explaining hwy enzymes are specfific .
19
Q
Temporary bonds form between the substrate molecule and the aminoacids on the surface ont he active site .
A
These temporary bonds , help to the lwoer the activation eneegyr of the reaction . Explaining how enzymes increse the reaction rate l.
20
Q
When scienists first looked t catalsts , they though the tertiary strucuutre of rhe active site is FIXED and does not chnge shape .
A
So esentaly ,t he susbtrate mooelcule slots perfectly into the active site .
-Scienitsts call this hte lock nd key hypothesis . / Lock and key theory .
21
Q
Later , scienitsts saw this model ws not ccurate . As the teriary strucuture of the active sire changes . as the substarte molecule approaches .
A
As the substarte starts to form bonds with the amino acids in the active sit . The tetriary strucuture of the enzyme , ajusts so that the active site moduls itself tghtly aroun the susbtrate .
22
Q
-This change in the tertiary sturucutrepof the enzyme , ensures tht the active site perfectly to the sbsrtate .
A
The bonds that the substarte forms witht he active site , helps to catalyse the reaction .
-Scienitsts call this the induced fit mdoel / induced fit hypothesis .
23
Q
Moleucles which are not the susbrtate canno formt he correct bonds to the correct bonds to the correct aminoa cids int he active site .
A
because of this , the tertiary strucuture of the enzyme DOES NOT CHANGE .
-Mening the hsap eof the active site does not adjust to fit the moelcule . Heping to explain why enxymes are specific for the subrate .
24
Q
check sheet for RECAP on both theories
A
even though experiments hsow induced fit model is correct .
25
During a reaction , if we plot the amount of product formed at different types we get a graph like this
...
26
Check the graph one - star one
Rapid inital rate ,a s you can see , at the start , the line is STEEP .
-This means that a large amount of product is produced in a short time .
-So the rate of the reaction is rapid initially .
27
Check graph one - star two
However , as the reaction continues , the line becomes less steep .
-Although , we are making product , the amount of product being formed in a given time is LESS then at the start .
-This tells us , that at this point , the rate of reaction has decreases (AKA - slows down ) .
28
Check graph - star three
At the end , the line is horizontal . Meaning no more product has been formed . So the reaction ha stopped .
29
Instead of measuring the amount of product being formed , we can measure the amount of substrate remaining .
Check the graph .
30
Checking graph two .
Again , we can see a rapid initial rate .
-Followed by the reaction slowing down .
-Then finally stopping
31
We can measure the rate of the reaction at any point , by drawing a tangent .
-Tangent is used to measure the rate of reaction at five seconds ( for example ) .
-Workout the gradient of the tangent by making a triangle .
(vertical side long -- > 27 mg so y has a value of 17 mg ) .
-Measure the length of x = 1.5-8s --->: so x has the value of 6.5 s .
-Calculate the gradient = y/x =n 17/6.5 = 2.62mg/s (3sf)
32
EXAM - explain the shape of the graph
KEY ; rate of the enzyme controlled reaction , depends on the frequency of successful collisions between the substrate and the active site .
~frequency " means the number of successful collisions .
33
Star one of graph three
At the start of the reaction , we have a large amount of substrate molecules . Meaning , there is a high frequency of successful collisions between the substrate and the active site .
-Giving a rapid rate of initial reaction .
34
Star two of graph three
As the reaction takes place , some of the substage is converted to product . Meaning the amount of substrate molecules falls .
-So the chances of a Subrata molecule colliding with he active site decreases .
-making reactions lowdown .
35
star three of graph three
Finally , at a certain point , all of the substrate molecules have been converted to product .
-There are no more substrate molecules left to collide with he active site .
-At this point k the reaction stops .
36
-We can calculate the rate of an enzyme controlled reaction , by plotting the amount of product formed against the time .
-We can then draw a tangent at the point of the reaction we are interested in .
-Select an enzyme to calculate the amount of product formed with time .
-We then , repeat this , using a range of temperatures . Then , we draw tangents to measure the rate of reactions at each temperature .
KEY ; - important that we draw the tangents at the same point for each reaction .
37
check graph for sample results
-each of these graphs represent the SAME enzyme controlled reaction .
-Just changed temperature for each reaction .
-As we increase the temperature , up to 40 degrees , we increase the rate of reaction .
-HOWEVER , if we increase the temperature to 50 degrees , we get a different reaction .
-At 50 degrees , the reaction is much slower . At higher temperatures than this , the enzyme may not function at all.
38
key ; when an enzyme denatures , due to high temperatures , it cannot renature if we cool it back down , why ?
As it's tertiary structure has changed so much that it cannot be renatured .
39
What is the temperature coefficient , check sheet for the equation .
check sheet for the equation
1. Measure the rate of the reaction , at a certain temperature (20 degrees ) .
2.We then measure the rate again , at a temperature ten degrees higher . (30 degrees ) .
40
What do we find when working out the temperature coefficient ?
Generally , what we find is that if we increase the temperature by ten degrees , the rate of an enzyme controlled reaction DOUBLES .
-Meaning the value of Q10 is usually has a value of 2 .
-HOWEVER - this does not apply for enzymes that are above the optimum temperature , as at that point the enzymes denature .
41
The pH of a solution depends on the concentration of hydrogen ions , Which are also called h+ ions .
-Solution with a low pH , (pH 2 ) , has a high concentration of hydorgen ions .
-Higher pH --> low concentration of hydrogen ions .
42
check the graph , that measures the rate of an enzyme at different pH .
-each enzyme works the fastest at an optimum PH .
(for this enzyme = 7 ) ---> this could be an enzyme in salivary glands .
-if the optimum ph. is 2 then the enzyme may work in an acidic environment like the stomach .
-If the pH change as away from the optimum ph. , then the rate of reaction decreases .
43
pH depends on the concentration of hydrogen ions present .
what can hydrogen ions bond with in an enzyme ?
-Hydrogen ions can bond with the R groups of amino acids in he protein .
-This includes amino acids within the active site , which form temporary bonds to the substrate .
-As this can prevent the R groups from bonding with the substrate , this can reduce how frequently the substrate binds to the active site --> reducing the rate of reaction .
44
Hydrogen ions also bond with the R groups of amino acid in the rest of the enzyme molecule .
The effect of this , can be to break the bonds, holding the tertiary structure of the enzyme in place .
45
example shown .
-check sheet , shows ionic bond between two amino acids on different parts of the enzyme molecule .
REMEMBER ; ionic bonds form between two charged R groups .
-f Ph falls the concentration of hydrogen ions increases . and the bond breaks (shown in the picture )
46
check sheet , what happens if the ph rises?
this causes the concentration of hydrogen ions to decrease and the bonds break .
-So as you can see , changing the pH can break the bonds which are essential for the enzyme's tertiary structure
-This can change the shape o f the active site , making it less likely for the substrate to attach succesfully .
47
What might happen if the ph. changes significantly ?
The active site may change shape so much that it is no longer complementary to the substrate and therefore the enzyme has now denatured .
48
RECAP ; what does the rate of an enzyme-catalyseda reaction depend on?
-It dependso n the frequency of collisions between the substrate molecules and the activ ste of the enzyme .
49
What is frequency ?
Frequency is the nber of collions per seocnd .
-shown nu,ber of enzyme oemlecules and their susbtare.
-Because the substrate cocnentration is LOW , we have a LOW FREQUECY of collisons between the substarte and the active sir .
-so the rate of rection is realtvely low ..
50
But then , what wull happen if we doubled subrtate concentration
meaning the frequecy of colliosns also doubles . Between the substarte molecules and the active site doubles . so the rate o reaction also doubles .
51
3. noe if we were to double substare concnetrationa gain
again , this doubles the fequency of collions between subratceat active site cusing the rte of rection to double .
52
Check the graph for this
As you can se , we porduce a grpah wth striaght line through xero .
-Thi means that the rate of revviton of an enxue catalyse ea tion is directly proporional to the subtrate concentratio . (double the susbrtae cocnentration rate of rection doubles )
53
What happens if we continue to increase substarte concentration ?
Then there comes to a point where the trate stops incresing any furhter .
-At this point ,t he enxme is working t its FSTEST rate , scineits cl this VMAC .
-AT ANY GIVEN POINT , EVERY ACTIVE SITE WILL BE COLLIDING WITH SURATE MOELCULE .
54
-What will happen if we add more substrate after vmax ?
xAs there re no free active site , for the extra substrate moleucles to collide with .
-Now , any increase in substrat eocncetraation will not increase rate of reaction any furhter .
-Scineitsts say that enzyme is saturated .
55
effect of enxyme cocnentration 1
Imagie a low cocnentration of enzyme meolcules .
-But a very large concentration of subrtae moelcules .
-All of the activie sites will be COLLIDING with subrtate moelcules ll the time .
-SO , at any tie , a large number of substare moelcules will be unable to collide with a free acive sites .
-Meaning the rate of reaction will be RELATIVLEY LOW .
56
effect of enzme concentration 2
If exnzyme concnetration doubles ,t hen the number of active sites doubles , DOUBLIGN the frequency of collisons between subsatretes and ctive sites .
-So thi odubles the rate .
-just like before , the rte i proprotional to enzyme cocnentration .
-PROVIDED that theire is more subsrtate than enzyme .
57
Effect of enzym cocn 3
-What will happen if the amoun of substren if the amount of substrate becomes limtiied .
-Then increasing enxym cocnnetration further will no longer increse the rate .
-As there won'te enough sbstarte necues to collide with all od the avaiable acrive sites .
58
KEY ; the sustarte is not the only moelule tha can bind to the active site . ( moelcules with a similr strucututr to the usbsrtate )
However , as iti s not the susbrtrat , no reactui can hppen . So after a while it leaves the active sites .
59
KEY ; by occuping the active site , this moelcles prevents the sacutl subrstate from colldiigng with the active site .
BECUSE , the frequency f colslisons between the subsrtate and the active site is reduced .
-yhe effect of this moelcle is that it reduces the rate of reaction . SCIENITSTS CALL THIS COMPETIVIE INHIBITORS .
60
example of competitive inhibiotrs
succinate is the substarte for an enxyme inovoleved in respiration .
Maalonate has a simialr strucutr eto succinate .
-SO , malonate acts as a competiie inhibort , preventign the succinate form coldiing with the active site of the enzyme .
-Meaning , Maloante can ihbiti respiration .
61
Competitive inhibitors comepte witht he susbstrate moelcules for the ctive site .
Meaning we can reduce the effect of a competitive inhibitor , by icnreasing the conentration of the substrate .
-example shown icnreading the cocnetration of susbtrate whle keeping conentration of comeptetivie inhirbotr .
-now there is a much greater concentration that a susbrtate moelcule , will occupy the active site ,r athe than the competitive inhibitor .
62
-By icnreasing the cocnentration of a susbrtate , we cn reduce the effect if ciopriiv einhirbots .
THIS IS SHOWN ON THE GRAPH ;
-shows enzyme in the bsnrcne of a competitive inhibitors .
-We re icnreasing substrate concentration meanin rate of revtio increes .
-As we have sene before ,a s susbrtate conc increases so deos rate of razction they are proprtional .
-However , ata certai substare cocnenration rate of reavtio ino longer increses .
-AS ALL OF TE CTIVE SITR ARE OCCUPIED .
-erat of reaction ais at max - vmax is achieved .
63
look ats econd line on grph , shows sam eexample but nowe have a competivie hnhibitor .
-competiive inhibotr reduces the rte of raction .
-point shown in yellwo arorow , inhibotr has reduced tnhe rate of reaction by 50 eprcent .
-comprd to the uninhibited enzyme .
-By temporrily blocking the active sitr , the comptiitive inhibrot prevents gthe susbtrate from bidnign and forming an enzyme susbrtate compe x.
64
HOWEVER , AS we increase the susbtrtae cocnentration , the effect of the competitive inhibitor is reduced .
example , at hiher substarte cocnentration shown in organe arrow , competitive inhibotr ahs only reduced rtae o reaction by 20 percent .
-at a very high susbsrate concentraiton ,r ate of rection , is almost hte same as with no competivie inibitor present .
65
many drugs are examples of competivitive inhirbotrs (1)
methotrexane is useed to treat certinc ancners .
-its rreverse competitive inhibort of an enzyme found in human cells .
66
many durgs are examples f competitive inhibitord (2)
anitbtiotic pencicillin . PENICLCCLIN IS A COMPEITIVE INHIRBOTR , USED IN THE SYNTHEISSI OF BCTERIAL CELL WALS .
-HOWEVER IT CN LIKE MEHTOTRECANE , PENCICLLIN BINDS REVERESLY ONTO THE ENZYME IT INHIBITS .
67
Key , some competitiv inhibitors bind irreversilbly to the ctive site of enzymes .
-Becuse it binds irreversilby to copmetitive inhibitros , it binds permantelty to hhe ative stes .
-We cnnot reverse the efect of these inhibotrs by incresing the subrtate concetration .
-That's besue once the irreversible compeitive inhibtor eneters the avyie site it never leabes no matters what the subrtate ocndnetration .
68
-unleike a competitive inhibtor , non comeptitive inhibitors do not bind to the ctive sute if a anzyme .
insted , non compeititve inhibitor binds to a different dite on hr znyme moelcule .
-scienitsts call this the LLOTERIC SITE .
*when the non compeittive inhibitor binds to the llosteric site , it cusrs the TERTIARY STRUCUTRRE of the ednzyme to chnge .
69
meanin g , the shap eof the active site changes , so it is no longer complemetary to the ubrtate .
substrate moelcule can no longer bind to the active site , to ofrm enzye substarte cimoex , Rhw wffect of this s hatit reduced the rate of reaction .
70
unlike a cmpeiive inhibitor , a noncomeptitive inhibtor does not have a similar strucutrue to the substrtae .
Thats because , a non ocmpeitiv einhitbor does not bind to the acive site .
key with noncompeittive inhitbor - the effect of the nonc oemptitiv eihbitor cannot be overcome by icnresing the susbrtate concentration wich i whon in the graph .
71
see graph - evem if we increse sub cocnenration , the non compeititive inhitbiro reduces the rate o recionb y the same amount .
Thats because ,t he noncomeptitive inhirbtor cuses the shape of the ctive site to t change ..
-so even if we icnese ,t he cocnentriton of subsrtate , the susbrtate moeleuels still cnnot bind he acive site
72
what is a metabolic pathway ?
it is a seiries of reactions al catalsyse dbyb enzymes .
-THe porduct made byt he first enzme is used s he subrtate for the secodn enzyme .
-the product md by the second nzyme is hten used s the susbrtate for the htird enxme and so on .
72
enzyme inhibittorn plays a really improtan role in cells reugualing meabolic pthways .
...
73
one example ofn metabolic pathways in cells
many exMPLES OD MRbolix patwhays in cells . some metabolic pathways breakdown a moelucle for exaple in rpsiraitn --> glucoise broken odwn to relase energy .
73
another example o metabolic pthways
in other mteabolic patwhasys compelx moeleueces are built up from smaller ones . Int he prodcuion of certain aminoa cids .
-meabolic pathwyas such as htese are tighlty ontroleld .
-oine xample hown , the amino acid made byt his apthway will be nneeded witht he syntehsis of proteins .
74
however , udner certain condtiiosn , portein syntehss cn slow down . Now ,t he cell will not reqruie alrg amounts of of the mino acid .
If the pTHY IS ALLOWED TO RUNA T ITS NORAL RAT , THEN THE AMINO ACID WOULD BUILD UP PINT HE CELL.
-THIS OWULD CAUSVALUEBE ENERGY ??
-SO THE CELL NEEDS OT REDUCE THE RATE . oF THE WHOLE METBAOLIC PATHWAY , TOD O THAT THE CELL WOUDL USE END PRODUCT INHITITON .
75
iN END PRODUCT INHIBTION , WHAT HAPPENS ?
the final product in the patwhay ihibits n enearly stage enzyme .
-increasing the effet of this rection , the raye of the metabolic pathway .
76
end product inhibittion IMAGINE
imagine , in this example , that hte cell hs a very lw rte of proteins yntehsis .
-Tht mens the cell does not require large amount so the amino acid .
-as the level of aminoa cid INCRASES , th aminoacid ataches and inhiits the enzym .
-because enzyme 1 is he first eznyme in the pahtway ,the rate of the waht pathwy the whole pathay is nwo reduced .
77
if the cell increases the elvel of portein syntehsis , then it willuse the mino acids to mke porteins .
nd the level of amino acids will decrease .
-BECAUSE , there is now less amino acids , present , there is less inhibtion of enzymes so the rate of the whole emetabolic pathway icnreases , making more amino acids for proteins yntehsis .
78
end porduct inhidbiton is used widely int he cell to regualt a rane of metabolic pathys example remot srespiration
ed producct of resprition is ATP ,
-*Whch transfers energy around thr cell .
-ATP pis an end product inhibter of an earlys tage enzyme in resprition .
--IF THE LELVEL of atp becomes TOO HIGHT , it inhits the erly stage enzyme and cuses ther ate of reaction to decrese
-THIS CUSSES the lvevel of atp to fall bac with range .
78
KEY POINTS (1)
end prodocut inhibtitord e.g negative feedback .
-as it use to keep the leel of key moeleuecles within a set rnage .
-if the leveel falls then end pordut inhtibitorn brings the leveels ack to the rnage . s
79
key points (2)
end prorduct inhibtion , is an example of non coemptitive inhibtiton .
As end product inhiiotn tkes palce rthrogh the allsoteric ctive sit of the enzyme .
79
Many tpxins (poiosns ) exert their effect because thier inhibit or inaictivte enzymes r effect bbeuase heir inhibit or inacitivate enzymes . here are some examples
...
80
cyanide
potassium cyanide (KCN) is highly toxic bvause it inhibits areobic resipiration . It also inhibits catalsse .
-When ingested , KCN is hdyrolysed to producehydorgen cyanide ,a very toxic gs ha xcan readily dissociate inot h+ and CN- ions .
-THe CN- ions bind irreversibly to an enzyme found in mothconiora and inhibit the final stage of aerobic resprition .
-Becuase the finals tage is inhibited , erler stages cannot run and aerobic respiration sotps .
81
Snake venom
the venom of a green mamaba snake contains a checinal that ihibits the enzyme AChE , this enzyme is improtant at neuromsucular synapes to break down the neurtornsmieeter ACh .
-If this enzyme is inhibtied , the ACh stays attached to repceptors on the m sucle memebran and keeps he msucle conracged .
-This cuases paralsysis ,a s moemnt dpends on the musclebseing bale to contrcata nd relax alenraely .
-If he msucle s involed in brethign are paralysed ,t hen victims duie fom suffocation .
82
Medicianld rugs acting bye znyme inhibiton - Aspririn
thid durg hs obeen used ofr over 3k year
-and mrketed as aspririn since the late 19th centry . Professor john ad gang discovered tat saliccylic acid binds to enzymes h catalskye the formation of prostaglndinds .
-Thus it precents the formaiton of prosaglandinds ha are cell-signalling meolcules produced y celsl when tisuse are infecd or damaged .
-prostaglandins make enrve cells mroe snenitive ot pain and icnrease swelling during inflamamiton .
-Aspirin can lso reduce the risk of lood clos forming an amny people take a low dose o reduce ris of stoeks .
*however under12 d o not tkae as i can damage stomach lining .
83
ATPase inhibtors
extracts from pruple focve been used for centuries to treat heart filur and arial arryhtyhima .
-the chiemcals are now identiied as cardicaic gylcosides also known as digitalis .
-they ijhits the sodium potassim pump in the cell memebrnaes o heart muscle cells ad lpow mroe clailcium ions ot ener the cells .
-calcium ions increase mcuslce contraction and this strenhes the heartbeat .
84
ACE inhibitors
Tehse are meidcal drugs that inhibit the angiotenissn converting enzyem , which nromallyoperaed in a metbolci pathay that unltimtel increases your blood pressure . They re used ;
-To lower blood pressures in pateints with hypertensions who canno ake beta-bockes .
-To ret heart failure - a low dose is given at first a dn the patient;s blood pressure is chekce dinc ase it falls too lwo .
-To minimise the risk of a second hert attck o ro a sroke in apteints hwo have suffered a mycoardial infarciton .
85
protease inhibitors
portease inhibtiros sucha s amprenavir and ritonavir are used to treat some viral ifneictions . Theey rprvent hte replciation of the virus prticles within the hos cells , by ihibiting proese enzymes so the viral coats annot be made . These inhibitros odtenh inhibit viral proease enzymes bc ompetitive inhibition .
85
nucelsoide reverse trascnritpae inhibtors
many of the antiviral drugs such as zidovudine and abacadivir asued to ret patients ho re HIV postive are nucslide rebsrse trasncirptiae inhibtors .. They inhibti enzmes involed in making DNA using the viral RNAa as a template
86
87
Many enzymes function in partnership with another chemical what is this called ?
Cofactors
88
What is the cofactor for the hyroduksid of starch and why ?
.
For this reacfion to happen. , a chloride ion had to attach ti the analyse molecule .
Without the chloride ion the amylase cannot catalyse the reaction . So in this case , the chloride ion is acting as a cofactor.
89
Key : chloride is not a substrate for amylase but …
It is required for amylase she to catalyse the reaction.
90
What is chloride ?
It is a simple mineralnion we get from our diet
HWOEBER many cofactors are complex organic molecules
Organic means based on carbon
NAD RXMAPLE
91
What is nad
Large organic molecule which temporarily ninde to many of the enzymes invoked in respriarion and
ROLE OF NAD AIS TK TRANDFER HUDIRHEN STOMS FROM MOEOCILE TO AKOFJER .
92
What happens when a cofactor is a large organic molecule ?
Sceineifs call it a coenzyme
Many coenzymes come from vitamins in our diet
Nad niacin b3
93
So cofactors can be
Small like chloride ion
Large organic molecules like nad coenzymes
94
consolidation on co factors
-during an enzyme talyed reaction , presenc of certin ions that bind to eithrer subrtate or enzme may ease the formation of the eznyme substrate compelx .
therefore increase the rae of an enzyme catalysed reaction /
-some co facorsa act as co substrtaes theya dd the subtrate together form the correct shape oto b dint ot hte ctive siete .
-some coftors change the distrubtiono ont he surface o the substrate moelcule or ont he surface of he enzymes activie site nd me the teporarybonds int he enzyme subrse compelx easier to form.
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lock nd key hypothesis consolidation emegrency card
-the substarte and enzyme moelcules each have kienitic energya nd are constantly mvong radnoly .
-if a substarte moelcule successfully collides with a enzyme moelcule then tan enzyme substartae compelx forms s the usbrtaate moelcule fits inot the complemenry hsaped active site ont he enyme meolcule .
-the usbstae moecules are iether boken down or ilt up and form enzme product compelx while in the ctie site .
-product moelcuels leave and ene meolcuel now ble to for more esc .
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induced fit hypothesis emergency crd
the active site still has a shape complementary to the shape of he surtrae meocluels , but upon bining the subtle changes of shape of he side chains (r groups ) of he amino cid , that make up the active sites give a more precise informaiton tha exactly fits th subsrtre oeclue .
-moudlign helps the subratte bind more effectively to th ctive site
-an enzyme substrta ecompelx is formed and noncovlne tbodns likehydorgen bonds ionic attractions and hydrophobic interactions bind to the subrtat emeoclue in the active site .
-when subsubstrate noecules have been converted into product moelcule thehy arestil ina ctive sie .
-enue now is fre to catlayse naotet type of reactionw ith another moelcule of same time .
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what does heat do to meolcules
both types of meoclulke snezyme aund substare they GAIN KINEITC ENERGY WHICH WHAT AMKES HTEM FMOVE SFASTE RINCREAING NUMBE ROF SUCCWSUFL COLLISON FFREUQNEYC PER SECOND
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HEAT MAKES MOELCULES vibrate
-MEANING SOME OF HRW EAK BONDS SUCH AS HYDROGEN BONDS AND IONIC BODNS HA HOLD THE TERAITRYS TRUCUTE BREAK ,
SO SUBSTAE DONT FIT DENUTED INNIT
-but he tpriamrys trucure is not alteredd , GTHR PORIN HSD DU UNOFLRD LOTS IS 3D SHAPE
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enzymes that are very high temperature ?
-thier enzymes are heat stable .
-they have more disulifde bonds that do not break with heat and keep the shape of portein moleucle stbale .
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Effects on temptrue grph GRPH GOING ON REACTION
-between a nad increasing temperture increses the rate of rectiond ue to increased kinetic energy .
-increasing temperatue beyond the optimum b temperature reduces the rate of tection due to the breaking of bonds holding the enymes tertirtry strucutre in plae .
c- at c teher eis nor etion because the enzyme is denatured .
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what is ph ?
oh indicate whether a usbstance is cidic or alkaline or netural .
aicids suh s hdyocloic acid sissociai show .
-lcic avid disociate ino h+ and lactate
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buffers in biology
-buffer is somethign tht resits hte vhsge int he ph , as certain chemicals in our blood thathep resi changes in the ph .
-these chemicals canodonte or ccept hydrogen ioons .
*-some proteins , such s haemoglobin cana slod onate or accpt protons and so ac s buffers
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how changes in ph affect bond within moelcule
a hyforghn ion which is a porton has a positive itis attracted toards negativel chagred ions , moelcules or parts of moelcules .
-partiuclry the active site int he correct shape o tha th substfrate moelcule will fit into it .
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how chnges in ph affect bond within nomoelcule
excesshydrogen ions ions ill interfere with the hydorgen bonds and ionic forces and so the active site of the enzyme moelculewillc hange hape .
-If the substrate moelucle does not fi well into the ctive site , then the rare of reaction tht the enzyme caalyses will lowoered .
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optimum pH
-enzymes wor extraceullarly may hae optimum pH 7 during digestion for example during digetion .
-foood passes into stomch hcl secreted givign a low ph . Oone of the is ficton is to illbacteria nd other pathogen in the food .
1-2 CIDIC LO;; BACEIRA IN PATHOGENS IN FOOD
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EFFECT OF INCREASING SUBSTRATE COCNENTRAION
-increasing substrate cocnenration eds o increased reaction rate .
-substrae cocnentration is the limiting factor .
-ALL ENZYMES present are working at maximum rat e .
-subsrarte cocnentrtion is no longer limtiign rectio anogher factor is ilimign the reaction
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enzyme degradation
the protein componen of living cells i constanly beign turned ober .
-cells are continuously degrding od enxyme meocuels to their components minoa cids ,
there are advanatges ;
-elimination of abornamlly shaped proteins that might itgherwise accumualed and harm the cell. ]
-regultion of meabolis in he cells by elimianigg uspelous .
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enzyme cocnentration graph
enzyme cocnentration is the limiing fcor .
-if substrate cocentration whih is now the limiting factor , is increases then the rate of reaction can increase .
ARGH jus page 115
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ditingiuish the idffferenc ebeteern adp and tp
adp --> adneniene (base) ribsoe (suagr)
atp --> adnenien tripohase tp consiss of dnnenie ribosie and 3 phospahte gourps .
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