BSC 2010 Ch 8 Lecture Presents Metabolism

8/18/2019 BSC 2010 Ch 8 Lecture Presents Metabolism

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CAMPBELL

BIOLOGYReece • Urry • Cain • Wasserman • Minorsky • Jackson

© 2014 Pearson Education, Inc.

TENTH

EDITION

CAMPBELL

BIOLOGYReece • Urry • Cain • Wasserman • Minorsky • Jackson


TENTH

EDITION

8An Introduction

to Metabolism

Lecture Presentation by

Nicole Tunbridge and

Katleen !it"#atric$


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© 2014 Pearson Education, Inc.© 2014 Pearson Education, Inc.

The Energy of Life

Te li%ing cell is a &iniature ce&ical 'actory(ere tousands o' reactions occur

Te cell e)tracts energy stored in sugars and

oter 'uels and a##lies energy to #er'or& (or$

*o&e organis&s e%en con%ert energy to ligt, as

in biolu&inescence


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!igure 8.1


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!igure 8.1a


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Concept 8.1: An organisms metabolismtransforms matter and energy! sub"ect to thela#s of thermodynamics

Metabolism is te totality o' an organis&+s

ce&ical reactions

etabolis& is an e&ergent #ro#erty o' li'e tat

arises 'ro& orderly interactions bet(een

&olecules


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$rgani%ation of the Chemistry of Life intoMetabolic &ath#ays

- metabolic path#ay begins (it a s#eci'ic&olecule and ends (it a #roduct

Eac ste# is cataly"ed by a s#eci'ic en"y&e


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!igure 8.N01

En%yme 1 En%yme ' En%yme (

)eaction 1 )eaction ' )eaction (&roduct*tarting

molecule

A + C ,


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Catabolic path#ays release energy by brea$ingdo(n cole) &olecules into siler coounds

/ellular res#iration, te brea$do(n o' glucose

in te #resence o' o)ygen, is an e)ale o' a

#at(ay o' catabolis&



Anabolic path#ays consu&e energy to buildcole) &olecules 'ro& siler ones

Te syntesis o' #rotein 'ro& a&ino acids is an

e)ale o' anabolis&

+ioenergetics is te study o' o( energy 'lo(s

troug li%ing organis&s



-orms of Energy

Energy is te ca#acity to cause cange Energy e)ists in %arious 'or&s, so&e o' (ic can

#er'or& (or$



inetic energy is energy associated (it &otion /eat 0thermal energy is $inetic energy associated

(it rando& &o%e&ent o' ato&s

or &olecules

&otential energy is energy tat &atter #ossesses

because o' its location or structure

Chemical energy is #otential energy a%ailable

'or release in a ce&ical reaction

Energy can be con%erted 'ro& one 'or& to anoter



!igure 8.2

A di2er has more potential

energy on the platform

than in the #ater.

,i2ing con2erts

potential energy to

3inetic energy.

A di2er has less potential

energy in the #ater

than on the platform.

Climbing up con2erts the 3inetic

energy of muscle mo2ement

to potential energy.



Animation: Energy Concepts



The La#s of Energy Transformation

Thermodynamics is te study o' energytrans'or&ations

-n isolated syste&, suc as tat a##ro)i&ated by

liuid in a ter&os, is unable to e)cange energy

or &atter (it its surroundings

In an o#en syste&, energy and &atter can

be trans'erred bet(een te syste& and its

surroundings rganis&s are o#en syste&s



The First Law of Thermodynamics

-ccording to te first la# of thermodynamics,te energy o' te uni%erse is constant

Energy can be transferred and transformed,

but it cannot be created or destroyed

Te 'irst la( is also called te #rinci#le o'

conser%ation o' energy

!i 8



!igure 8.

0a 0b-irst la# of thermo4

dynamics

*econd la# of thermodynamics

Chemical

energy

/eatC$'

/'$

!igure 8 a



!igure 8.a

0a -irst la# of thermodynamics

Chemicalenergy

!igure 8 b


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!igure 8.b

0b *econd la# of thermodynamics

/eatC$'

/'$


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The Second Law of Thermodynamics

3uring e%ery energy trans'er or trans'or&ation,so&e energy is unusable, and is o'ten lost

as eat

-ccording to te second la# of thermodynamics

Every energy transfer or transformation increases

the entropy (disorder) of the universe


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Li%ing cells una%oidably con%ert organi"ed'or&s o' energy to eat

*pontaneous processes occur (itout energy

in#ut tey can a##en uic$ly or slo(ly

!or a #rocess to occur (itout energy in#ut,

it &ust increase te entro#y o' te uni%erse


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Biological Order and Disorder

/ells create ordered structures 'ro& less ordered&aterials

rganis&s also re#lace ordered 'or&s o' &atter

and energy (it less ordered 'or&s

Energy 'lo(s into an ecosyste& in te 'or& o' ligt

and e)its in te 'or& o' eat

!igure 8 4


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!igure 8.4

!igure 8 4a


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!igure 8.4a

!igure 8.4b


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!igure 8.4b


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Te e%olution o' &ore cole) organis&s doesnot %iolate te second la( o' ter&odyna&ics

Entro#y 5disorder6 &ay decrease in an organis&,

but te uni%erse+s total entro#y increases


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Concept 8.': The free4energy change of areaction tells us #hether or not the reactionoccurs spontaneously

7iologists (ant to $no( (ic reactions occur

s#ontaneously and (ic reuire in#ut o' energy

To do so, tey need to deter&ine energy canges

tat occur in ce&ical reactions


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-ree4Energy Change! G

- li%ing syste&+s free energy is energy tat cando (or$ (en teerature and #ressure are

uni'or&, as in a li%ing cell


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Te cange in 'ree energy 5G6 during a #rocessis related to te cange in ental#y, or cange in

total energy 5H 6, cange in entro#y 5S6, and

teerature in Kel%in units 5T 6

G = H− T S

$nly processes #ith a negati2e 5G are

spontaneous and! spontaneous processes can

be harnessed to perform #or3


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-ree Energy! *tability! and E6uilibrium

!ree energy is a &easure o' a syste&+s instability,its tendency to cange to a &ore stable state

3uring a s#ontaneous cange, 'ree energy

decreases and te stability o' a syste& increases

Euilibriu& is a state o' &a)i&u& stability

- #rocess is s#ontaneous and can #er'or& (or$

only (en it is &o%ing to(ard euilibriu&

!igure 8.9


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7 More free energy 0higher G

7 Less stable7 reater #or3 capacity

7 Less free energy 0lo#er G 7 More stable7 Less #or3 capacity

0a ra2itational motion 0b ,iffusion 0c Chemical reaction

The free energy of the

system decreases

0∆G


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7 More free energy 0higher G 7 Less stable7 reater #or3 capacity

7 Less free energy 0lo#er G 7 More stable7 Less #or3 capacity

The free energy of the

system decreases

0∆G


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0a ra2itational motion 0b ,iffusion 0c Chemical reaction


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-ree Energy and Metabolism

Te conce#t o' 'ree energy can be a##lied to tece&istry o' li'e+s #rocesses


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Exergonic and Endergonic Reactions inMetaolism

-n eergonic reaction #roceeds (it a netrelease o' 'ree energy and is s#ontaneous

-n endergonic reaction absorbs 'ree energy 'ro&

its surroundings and is nons#ontaneous

!igure 8.:Eergonic reaction: energy released0a


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Eergonic reaction: energy released!

spontaneous

Endergonic reaction: energy re6uired!

nonspontaneous

0a

0b

- r e e e n e r g

y

- r e e e n e r g y

)eactants

)eactants

Energy

Energy

&roducts

&roducts

Amount of

energy

released

0∆G 9

&rogress of the reaction



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E!"iliri"m and Metaolism

;eactions in a closed syste& e%entually reaceuilibriu& and ten do no (or$

!igure 8.


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∆G


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/ells are not in euilibriu& tey are o#en syste&se)#eriencing a constant 'lo( o' &aterials

A defining feature of life is that metabolism is

ne2er at e6uilibrium

- catabolic #at(ay in a cell releases 'ree energy

in a series o' reactions 5li$e cellular res#iration6

!igure 8.8


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0a An open hydro4

electric system

0b A multistep open hydroelectric system

∆G


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Concept 8.(: AT& po#ers cellular #or3 bycoupling eergonic reactions to endergonicreactions

- cell does tree &ain $inds o' (or$

/e&ical

Trans#ort

ecanical

To do (or$, cells &anage energy resources by

energy coupling, te use o' an e)ergonic #rocess

to dri%e an endergonic one

ost energy cou#ling in cells is &ediated by -TP


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The *tructure and /ydrolysis of AT&

AT& 0adenosine triphosphate is te cell+senergy suttle

-TP is coosed o' ribose 5a sugar6, adenine

5a nitrogenous base6, and tree #os#ate grou#s

!igure 8.=

Adenine


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0a The structure of AT&

0b The hydrolysis of AT&

Adenosine triphosphate 0AT&

)ibose

Adenine

Triphosphate group

0( phosphate groups

Adenosine diphosphate

0A,&

Energy

Inorganic

phosphate

/'$


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;ideo: *pace4-illing Model of AT&


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;ideo: *tic3 Model of AT&


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Te bonds bet(een te #os#ate grou#s o' -TP+s tail can be bro$en by ydrolysis

Energy is released 'ro& -TP (en te ter&inal

#os#ate bond is bro$en

This release of energy comes from the

chemical change to a state of lo#er free

energy! not from the phosphate bonds

themsel2es


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/o# the /ydrolysis of AT& &erforms


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-TP dri%es endergonic reactions by#os#orylation, trans'erring a #os#ate grou# to

so&e oter &olecule, suc as a reactant

Te reci#ient &olecule is no( called a

phosphorylated intermediate

!igure 8.10


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0a lutamic acid con2ersion to glutamine

0b Con2ersion reaction coupled #ith AT& hydrolysis

0c -ree4energy change for coupled reaction

lutamic acid Ammonia lutamine

lutamin

e

lutamic acid &hosphorylated

intermediate

lu

=/(

lu

=/'

=/(

=/'

luluA,& &

i

A,& &i

=/'

lu

∆G AT& = >?.( 3cal@mol

∆G lu = +(.

3cal@mol

∆G lu = +(.

3cal@mol+ ∆G AT&= >?.( 3cal@mol

= >(.B 3cal@mol=et ∆G

=/(

lu AT&

AT&

∆G lu = +(.

3cal@mol

lu

1 '&A,&


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Trans#ort and &ecanical (or$ in te cell are also#o(ered by -TP ydrolysis

-TP ydrolysis leads to a cange in #rotein sa#e

and binding ability

!igure 8.11

T t t i * l t


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Transport protein *olute

*olute transported

0a Transport #or3: AT& phosphorylates transport proteins.

Mechanical #or3: AT& binds nonco2alently to motor

proteins and then is hydroly%ed.

&rotein and 2esicle mo2edMotor protein

Cytos3eletal trac3

AT&AT&

A,& & i

A,& & i

& i&

AT&

0b

;esicle

Th ) ti f AT&


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The )egeneration of AT&

-TP is a rene(able resource tat is regenerated

by addition o' a #os#ate grou# to adenosine

di#os#ate 5-3P6

Te energy to #os#orylate -3P co&es 'ro&

catabolic reactions in te cell

The AT& cycle is a re2ol2ing door through

#hich energy passes during its transfer from

catabolicto anabolic path#ays

!igure 8.12


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Energy from

catabolism

0eergonic! energy4releasing processes

Energy for cellular

#or3 0endergonic

energy4consumingprocesses

A,& & i

/'$AT&

C t 8 E d t b li


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Concept 8.: En%ymes speed up metabolicreactions by lo#ering energy barriers

- catalyst is a ce&ical agent tat s#eeds u# a

reaction (itout being consu&ed by te reaction

-n en%yme is a catalytic #rotein

>ydrolysis o' sucrose by te en"y&e sucrase is

an e)ale o' an en"y&e?cataly"ed reaction 5ne)t

slide6

!igure 8.N02


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*ucrose

0C1'/''$11

lucose

0C/1'$

-ructose

0C/1'$

*ucrase

Th A ti ti E + i


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The Acti2ation Energy +arrier

E#ery chemical reaction etween molec"les

in#ol#es ond rea$ing and ond forming

Te initial energy needed to start a ce&ical

reaction is called te 'ree energy o' acti%ation,

or acti2ation energy 5E -6

-cti%ation energy is o'ten su##lied in te 'or& o'

ter&al energy tat te reactant &olecules absorb

'ro& teir surroundings

!igure 8.1


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Transition state

)eactants

&roducts


EA

∆G


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Animation: /o# En%ymes


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/o# En%ymes *peed Dp )eactions

En"y&es cataly"e reactions by lo(ering te

E - barrier

En"y&es do not a''ect te cange in 'ree energy

5G6 instead, tey asten reactions tat (ould

occur e%entually

!igure 8.14


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Course of

reaction

#ithouten%yme

Course of

reaction

#ith en%yme

EA #ith

en%yme

is lo#er

EA

#ithout

en%yme

&roducts

)eactants

- r e e e n

e r g y

5G is unaffected

by en%yme


*ubstrate *pecificity of En%ymes


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*ubstrate *pecificity of En%ymes

Te reactant tat an en"y&e acts on is called

te en"y&e+s substrate

Te en"y&e binds to its substrate, 'or&ing an

en%yme4substrate comple

The reaction cataly%ed by each en%yme is

2ery specific


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Te acti2e site is te region on te en"y&e

(ere te substrate binds

Induced fit o' a substrate brings ce&ical grou#s

o' te acti%e site into #ositions tat enance teir

ability to cataly"e te reaction

!igure 8.19


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*ubstrate

Acti2e site

En%yme En%yme4substrate

comple

;ideo: Closure of /eo3inase ;ia Induced -it


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;ideo: Closure of /eo3inase ;ia Induced -it

Catalysis in the En%ymes Acti2e *ite


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Catalysis in the En%yme s Acti2e *ite

In an en"y&atic reaction, te substrate binds to

te acti%e site o' te en"y&e

Te acti%e site can lo(er an E - barrier by

rienting substrates correctly

*training substrate bonds

Pro%iding a 'a%orable &icroen%iron&ent

/o%alently bonding to te substrate

!igure 8.1:?1

1 '


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*ubstrates enter

acti2e site.

*ubstrates

*ubstrates are

held in acti2e

site by #ea3

interactions.

1 '

En%yme4substrate

comple

!igure 8.1:?2

* b t t t * b t t1 '


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*ubstrates enter

acti2e site.

*ubstrates

*ubstrates are

con2erted to

products.

*ubstrates are

held in acti2e

site by #ea3

interactions.

1 '

En%yme4substrate

comple

(

!igure 8.1:?

* b t t t * b t t1 '


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*ubstrates enter

acti2e site.

*ubstrates

*ubstrates are

con2erted to

products.

*ubstrates are

held in acti2e

site by #ea3

interactions.

1 '

&roducts are

released.

En%yme4substrate

comple

&roducts

(

!igure 8.1:?4

* b t t t * b t t1 '


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*ubstrates enter

acti2e site.

*ubstrates

*ubstrates are

con2erted to

products.

*ubstrates are

held in acti2e

site by #ea3

interactions.

1 '

&roducts are

released.

En%yme

En%yme4substrate

comple

Acti2e site

is a2ailable

for ne#

substrates.

&roducts

(

Effects of Local Conditions on En%yme Acti2ity


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Effects of Local Conditions on En%yme Acti2ity

-n en"y&e+s acti%ity can be a''ected by

@eneral en%iron&ental 'actors, suc as

teerature and #>

/e&icals tat s#eci'ically in'luence te en"y&e

Effects of Temperat"re and p%


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Effects of Temperat"re and p%

Eac en"y&e as an o#ti&al teerature in (ic

it can 'unction

Eac en"y&e as an o#ti&al #> in (ic it can

'unction

#ti&al conditions 'a%or te &ost acti%e sa#e 'or

te en"y&e &olecule

!igure 8.1<$ptimal temperature for

typical human en%yme

$ptimal temperature for

en%yme of thermophilic


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typical human en%yme

0(? C

$ptimal p/ for pepsin

0stomach

en%yme

$ptimal p/ for trypsin

0intestinal

en%yme

en%yme of thermophilic

0heat4tolerant

bacteria 0?? C

Temperature 0 C

p/9 1 ' ( ? 8 B 19

9 '9 9 9 89 199 1'9

0a $ptimal temperature for t#o en%ymes

0b $ptimal p/ for t#o en%ymes

) a t e o f r e

a c t i o n

) a t e o f r e a

c t i o n

&ofactors


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&ofactors

Cofactors are non#rotein en"y&e el#ers

/o'actors &ay be inorganic 5suc as a &etal in

ionic 'or&6 or organic

-n organic co'actor is called a coen%yme 4

coen%ymes include 2itamins

En'yme (nhiitors


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En'yme (nhiitors

Competiti2e inhibitors bind to te acti%e site

o' an en"y&e, coeting (it te substrate

=oncompetiti2e inhibitors bind to anoter #art o'

an en"y&e, causing te en"y&e to cange sa#e

and &a$ing te acti%e site less e''ecti%e

Examples of inhibitors include toxins, poisons,

pesticides, and antibiotics

!igure 8.18


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0a =ormal binding 0b Competiti2e inhibition 0c =oncompetiti2einhibition

*ubstrate

Acti2e site

En%yme

Competiti2einhibitor

=oncompetiti2e

inhibitor

Concept 8 : )egulation of en%yme acti2ity


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Concept 8.: )egulation of en%yme acti2ityhelps control metabolism

/e&ical caos (ould result i' a cell+s &etabolic

#at(ays (ere not tigtly regulated

- cell does tis by s(itcing on or o'' te genes

tat encode s#eci'ic en"y&es or by regulating

te acti%ity o' en"y&es

Allosteric )egulation of En%ymes


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Allosteric )egulation of En%ymes

Allosteric regulation &ay eiter inibit or

sti&ulate an en"y&e+s acti%ity

-llosteric regulation occurs (en a regulatory

&olecule binds to a #rotein at one site and

a''ects te #rotein+s 'unction at anoter site

)llosteric )cti#ation and (nhiition


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)llosteric )cti#ation and (nhiition

ost allosterically regulated en"y&es are &ade

'ro& #oly#e#tide subunits

Eac en"y&e as acti%e and inacti%e 'or&s

Te binding o' an acti%ator stabili"es te acti%e

'or& o' te en"y&e

Te binding o' an inibitor stabili"es te inacti%e

'or& o' te en"y&e

!igure 8.20

0a Allosteric acti2ators and inhibitors 0b Cooperati2ity: another type


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*tabili%ed

acti2e form

Inacti2e form

$scillation

=on4

functional

acti2e site

)egulatory

site 0one

of four

Allosteric en%yme

#ith four subunitsActi2e site

0one of four

Acti2e form

Acti2ator

*ubstrate

*tabili%ed

acti2e form

Inhibitor Inacti2e form *tabili%ed

inacti2e form

of allosteric acti2ation


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Cooperati2ity is a 'or& o' allosteric regulation

tat can ali'y en"y&e acti%ity

ne substrate &olecule #ri&es an en"y&e to act

on additional substrate &olecules &ore readily

/oo#erati%ity is allosteric because binding by a

substrate to one acti%e site a''ects catalysis in a

di''erent acti%e site

Feedac$ (nhiition


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Feedac$ (nhiition

In feedbac3 inhibition, te end #roduct o' a

&etabolic #at(ay suts do(n te #at(ay

!eedbac$ inibition #re%ents a cell 'ro& (asting

ce&ical resources by syntesi"ing &ore #roduct

tan is needed

!igure 8.21Acti2e site a2ailable Threonine

in acti2e site


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Isoleucine

used up by

cell

Isoleucine

binds to

allosteric

site.

Acti2e

site no

longer

a2ailableF

path#ayis halted.

En%yme 1

0threonine

deaminase

-eedbac3

inhibition

Intermediate A

Intermediate +

Intermediate C

Intermediate ,

En%yme '

En%yme (

En%yme

En%yme

End product

0isoleucine

Locali%ation of En%ymes


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y

*tructures (itin te cell el# bring order to

&etabolic #at(ays

*o&e en"y&es act as structural coonents

o' &e&branes

In eu$aryotic cells, so&e en"y&es reside in

s#eci'ic organelles 'or e)ale, en"y&es 'or

cellular res#iration are located in &itocondria

!igure 8.22


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Mitochondria

The matri contains

en%ymes in solution that

are in2ol2ed on one stage

of cellular respiration.

En%ymes for another

stage of cellular

respiration are

embedded in the

inner membrane

1 G m

!igure 8.N0b


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!igure 8.N09


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BSC 2010 Ch 8 Lecture Presents Metabolism

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Transcript of BSC 2010 Ch 8 Lecture Presents Metabolism