Principles of Biochemistry

1294 Pages·2008·179.141 MB·English

by  Lehninger A., Nelson D.L., Cox M.M.

HNI
PRINCIPLESO F BIOCHEMISTRY
FIFTH EDITION
David L. Ne l son
Professoro f Bio chemistry
Uniue rs ity of Wis c o nsin-Ma dis o n
Michael M. Cox
Profess or of Bi,oc hemistry
Uni,uersity of Wi,sconsin-Madi,son
l=
W.H.F REEMAANN DC OMPANY
NewY ork
4
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lllustrations: H.A DAMS TEINBERNGE;T WORGKR APHICS
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On the cover: RNA polymerase II from yeast, bound to DNA and in the act of transcribing it into RNA.
Imagec reatedb y H. Adam Steinbergu sing PDB ID 1I6Ha s modi.fledb y Seth Darst.
Library of CongressC ontrol Number: 2007941224
ISBN-139: 78-0-7167-7108-1
ISBN-I0 : 0-71 67- 7r 08-X
@2008b y W. H. Freemana nd Company
All rights reserved
Printed in the United States of America
First printing
W H. Freeman and Company
41 MadisonA venue
New York,N Y 10010
Houndmills,B asingstokeR G216 XS,E ngland
www.whfreeman.com
To Our Teachers
PauLR . Burton
Albert Fi,ntuolt
Wi,LLi,aPm. Jencks
Eugene P. Kennedy
Homer Knoss
ArtLtur Kornberg
L RobertL eltman
EarL K, I{elson
Dauid E, Sh,eppard
Harold B. Wti,te
DaVid L. NelSOn,b orni n FairmontM, innesorrae, -
ceived his BS in Chemistry and Biology from St. Olaf
College in 1964 and earned his PhD in Biochemistry at
Stanford Medical School under Arthur Kornberg. He
was a postdoctoral felLowa t the Harvard Medical School
with Eugene P. Kennedy, who was one of Albert
Lehninger's first graduate students. Nelson joined the
faculty of the University of Wisconsin-Madison h 1971
and became a full professor of blochemrstry in 1982. He
is the Director of the Center for Biology Education at
the University of Wisconsin-Madison.
Nelson's research has focused on the signal trans-
ductions that regulate ciliary motion and exocytosis in
the protozoan Parameci,um. The enzymes of signal
transductions, including a variety ofprotein kinases,a re
primary targets of study. His research group has used
enzyme purification, immunological techniques, elec-
tron microscopy, genetics, molecuiar biology, and elec-
trophysiologyt o study these processes Davi[d. Nelsoann dM ichaeMl .C ox
Dave Nelson has a distinguished record as a lecturer
and research superuisor. For 36 years he has taught an
intensive survey of brochemistry for advanced biochem- tions. At Stanford,h e beganw ork on the enzymesi n-
istry undergraduates in the life sciences. He has also volvedi n geneticr ecombinationT. he work focusedp ar-
taught a survey of biochemistry for nursing students, ticularly on the RecAp rotein, designingp uriflcation and
and graduate courses on membrane structure and func- assaym ethods that are still in use, and illuminating the
tion and on molecular neurobiology. He has sponsored processo f DNAb ranchm igration.E xplorationo f the en-
numerous PhD, MS, and undergraduate honors theses, 4,.rneso f genetic recombinationh as remained the cen-
and has received awards for his outstanding teaching, tral themeo f his research.
including the Dreyfus Teacher-Scholar Award, the Mike Cox has coordinateda large and active re-
Atwood Distinguished Professorship, and the Unterkofler searcht eam at Wisconsin,in vestigatingt he enzymology,
Excellence in Teaching Award from the University of topology,a nd energeticso f genetic recombination.A
WisconsinS ystem.I n 1991-1992h e was a visiting profes- primary focus has been the mechanism of RecA
sor of chemistry and biology at Spelman College. His protein-mediatedD NA strand exchanget,h e role of ATP
second love is history and in his dotage he has begun to in the RecA system,a nd the regulationo f recombina-
teach the history of biochemistry to r-mdergraduatesa nd tional DNA repair. Part of the researchp rogram now
to collect antique scientific instruments. focuseso n organismst hat exhibit an especiallyr obust
capacityf or DNA repair, such asD ei,nococcusr ad'i,odu-
MiChagl M. COXw asb orni n WlmingtonI,) elaware. rans, and the applicationso f those repair systemst o
In his first biochemistrcyo urseL, ehningerB'si ochem- biotechnologyF. or the past 24 yearsh e has taught (with
'istry
was a major influence in refocusing his fascination DaveN elson)t he suwey of biochemistryt o undergradu-
with biology and inspiring him to pursue a career in bio- ates and hasl ectured in graduatec ourseso n DNA struc-
chemistry. After graduating from the University of ture and topology,p rotein-DNAi nteractions,a nd the
Delaware inl974, Cox went to Brandeis University to do biochemistryo f recombinationA. more recent project
his doctoral work with MIIiam P Jencks, and then to has been the organizationo f a new courseo n profes-
Stanford in 1979 for postdoctoral study with I. Robert sional responsibilityf or fi.rst-yearg raduates tudents.H e
Lehman. He moved to the University of Wisconsin- has received awards for both his teaching and his
Madison in 1983, and became a full professor of research,i ncluding the Dreyfus Teacher-ScholaAr ward
biochemistry in 1992. and the 1989E Ii Lilly Award in BiologicalC hemistry His
Cox's doctoral research was on general acid and hobbiesi nclude gardening,w ine collecting,a nd assisting
base catalysis as a model for enz;,,rne-catalyzedr eac- in the designo f laboratoryb uildings.
vl
n this twenty-flrst century a typical sciencee ducation reproducibleo bservationsa,n dt he scientistm ust report
I
I often leavest he philosophicalu nderpinningso f sci- theseo bservationws ith completeh onesty.
enceu nstated,o r relies on oversimplifiedd efinitions.A s The scientific method is actually a collection of
you contemplatea careeri n sciencei,t may be usefult o paths,a ll of wtuch may lead to scientificd iscoveryI.n the
considero nce againt he terms science, scientist, and hypothesi,sa nd erperiment path,a scientistp osesa hy-
scientifie method. pothesis,t hen subjectsi t to experimentalt est. Many of
Science is both a way of thinking about the natural the processesth at biochemistsw ork with everyd ay were
world and the sum of the information and theory that re- discoveredin this manner.T he DNA structure elucidated
sult from such thinking.T he power and successo f sci- by JamesW atsona nd FrancisC rick led to the hypothesis
encef low directlyf rom its relianceo n ideast hat canb e that basep airjrg is the basisf or information transfer in
tested: information on natural phenomenat hat can be po\mucleotide sS,nthesisT.h is hlpothesis helpedi nspire
observedm, easureda, nd reproduceda nd theoriest hat the discoveryo f DNA and RNA pol5.'rnerases.
havep redictivev alue.T he progresso f sciencer estso n a Watsona nd Crick produced their DNA structure
foundationala ssumptiont hat is often unstated but cru- through a process of model bui,ldi,ng and calcula-
cial to the enterprise:t hat the lawsg overningf orcesa nd t'ion. No actual experimentsw ere involved,a lthough
phenomenae xisting in the universe are not subject to the model building and calculationsu sed data col-
change.T he Nobell aureateJ acquesM onodr eferredt o lectedb y other scientists.M any adventurouss cientists
this underlyinga ssumptiona s the "postulateo f objectiv- havea ppliedt he processo ferp\oration and obserua-
ity." The natural world can therefore be understoodb y t'ion as a path to discovery.H istoricalv oyageso f dis-
applying a processo f inquiry-the scientific method. covery (Charles Darwin's 1831 voyage on H.M.S.
Sciencec ould not succeedi n a universe that played Beaglea mongt hem) helpedt o map the planet,c atalog
tricks on us. Other than the postulateo f objectivity,s ci- its living occupants,a nd changet he way we view the
ence makesn o inviolate assumptionsa bout the natural world. Modern scientistsf ollow a similar path when
world.A usefiils cientiflcid eai s onet hat (1) hasb eeno r they explore the oceand epths or launch probest o
can be reproduciblys ubstantiateda nd (2) can be used other planets.A n analogo f hypothesisa nd experiment
to accuratelyp redictn ew phenomena. is hypothesi,sa nd deduct'ion. Crick reasonedt hat
Scientrflci deast ake many forms. The terms that sci- there must be an adaptor molecule that facilitated
entists use to describet hese forms havem eaningsq uite translationo f the informationi n messengerR NA into
differentf rom thosea ppliedb y nonscientistsA. hypoth- protein.T his adaptorh ypothesisle d to the discoveryo f
esesi s an idea or assumptiont hat providesa reasonable transferR NA by MahlonH oaglanda nd Paul Zamecnik.
and testablee xplanationf or one or more observations, Not all paths to discoveryi nvolve planrung.S erendip-
but it may lack extensivee xperimentals ubstantiation.A i,tg often plays a role. The discovery of penicilJin by
sci,enti,fi,cth eorA is much more than a hunch. It is an Alexander Fleming in 1928, and of RNA catalysts by
idea that has been substantiatedt o some extent and ThomasC echi n the early 1980sw, ereb oth chanced iscov-
provides an explanationf or a body of experimentalo b- eries, albeit by scientistsw ell preparedt o exploit them.
servations.A theory can be tested and built upon and is Irnpi,rati,on can alsol ead to important advancesT. he poly-
thus a basisf or further advancea nd innovation.W hen a merasec hainr eaction( PCR),n ow a centralp art of biotech-
scientiflct heory has been repeatedlyt ested and vali- nology, was developedb y Kary Mullis afler a flash of
datedo n manyf ronts,i t canb e accepteda s a fact. inspration dudng a road trip in northern Califomiai n 1983.
In one importants ensew, hat constitutess cienceo r These many paths to scientiflc discovery can seem
a scientiflc idea is defined by whether or not it is pub- quite different, but they have some important things
lished in the scientiflc literature after peer review by in common. They are focused on the natural world.
other working scientists.A bout 16,000p eer-reviewed They rely on reproducCbleo bseruat'ion anilor erperi-
scientific journals worldwide publish some 1.4 million ment. Nl of the ideas,i nsights, and experimentalf acts
articles eachy ear, a continuing rich harvest of informa- that arise from these endeavorsc an be tested and
tion that is the birthright of every human being. reproducedb y scientistsa n5,wherein the world. All can
Scientists are indiredualsw ho rigorouslya pply the be usedb y other scientiststo build new hypothesesa nd
scientific method to understand the natural world. make new discoveries.A ll lead to information that is
Merely having an advancedd egreei n a scientiflc disci- properlyi ncludedi n the realm of science.U nderstand-
pline doesn ot makeo nea scientist,n or doest he lack of ing our universer equires hard work. At the samet ime,
such a degreep revent one from making important sci- no human endeavori s more exciting and potentially re-
entific contributions.A scientistm ust be willing to chal- warding than trying, and occasionallys ucceedingt,o un-
lenge any idea when new findings demandi t. The ideas derstands omep art of the natural world.
that a scientista cceptsm ust be basedo n measurable,
vtl
first edition of Pnnctples oJB i,ochenuistry, v'ritten We are at the threshold of a new molecularp hysiol-
Albert Lehningert wenty-flve years ago,h as serveda s ogy in which processess uch as membrane excitation,
the starting point and the model for our four subsequent secretion,h ormonea ction,v ision,g ustation,o lfaction,
editions.O vert hat quarter-centuryt he world of biochem- respiration,m usclec ontraction,a nd cell movementsw ill
istry hasc hangede normouslyT. Wenty-flvyee arsa go,n ot a be explicablein moleculart ermsa ndw ill becomea cces-
singleg enomeh adb eens equencedn,o t a singlem embrane sible to genetic dissectiona nd pharmacologicaml anipu-
proternh ad beens olvedb y crystallographya,n d not a sin- lation. Knowledgeo f the molecular structures of the
$e hnockoutm ousee xisted.R ibozJrmehsa dj ust beend is- highly organizedm embrane complexes of oxidative
covered, PCR technology introduced, and archaea phosphorylation and photophosphorylation,f or exam-
recognizeda sm emberso f a kingdoms eparatefr om bac- ple, will certainly bring deepenedi nsight into those
teria Now,n ewg enomics equenceasr ea nnouncedw eekly, processess,o centralt o life. (Thesed evelopmentms ake
new protern structures even more frequently, and re- us wish we were young again,j ust beginningo ur careers
searchersh ave engineeredt housandso f djfferent lcrock- in biochemicalr esearcha nd teaching. Our book is not
out mice, with enormousp romise for advancesin basic the only thing that has acquired a touch of silver over
biochemistryp hysiologya, nd medicine.T his ffih edition the years!)
containst he photographso f 31 Nobell aureatesw ho have In the past two decades,w e have striven alwayst o
receivedth eirprizesf or Chemistryo r for Physiologor r Med- maintain the qualitiest hat made the original Lehninger
icine sincet hat first edition of Prhrciples of Binchemistry. text a classic-clear wdting, careftrle xplanationso f diffl-
One major challengeo f each edition has been to re- cult concepts,a nd communicatingt o studentst he ways
flect the torrent of new information without making the in which biochemistryi s understooda nd practicedt oday.
book overwhelming for students having their first en- Weh avew ritten togetherf or twenty yearsa nd taught to-
counter with biochemistry.T his hasr equired much care- gether for almostt wenty-flve.O ur thousandso f students
ful sifting aimed at emphasizingp rinciples while still at the Universityo f Wisconsin-Madisono ver those years
conveyingt he excitemento f current researcha nd its haveb een an endlesss ourceo f ideasa bout how to pres-
promisef or the future. The cover of this new edition ex- ent biochemistrym ore clearly;t hey havee nlighteneda nd
empli-fletsh is excitementa nd promise:i n the x-ray struc- rnspired us. We hope that this twenty-flfth aruLiversary
ture of RNA polymerasew, e seeD NA, RNA, and protein edition will erLlightena nd inspire current studentso f bio-
in their informationalr oles,i n atomrcd imensionsc, aught chemistrye verywherea, nd perhapsl ead someo f them to
in the central act of in-formationtr ansfer. Ioveb iochemistrya s we do.
MajoRr ecenAtd vanciensB iochemistry
Every chapter has been thoroughly revised and up- by plants, and of bird feather pigmentsd erived
dated to include the most important advancesin bio- from coloredl ipids in plant foods (Chapter1 0)
chemistryi ncluding:
Expandeda nd updated sectiono n lipid rafrts and
r Conceptso f proteomes and proteomics, caveolae to rncluden ew material on membrane
introducede arlieri n the book (Chapter1 ) curvature and the proteins that influencei t, and
introducng amphitropic proteins and anmrlar
r New discussiono f amyloid diseasesi n the
Iipids (Chapter1 1)
context of protein folding (Chapter 4)
New section on the emergingr ole of ribulose
r New section on pharmaceuticals developedf rom
5-phosphate as a central regulator of $ycolysis
an understandingo f enzymem echanismu, sing
andg luconeogenes(isC hapter 15)
penicillina nd HIV proteasei nlLibitorsa s examples
(Chapter6 ) New Box 16-1, MoonlightingE rzymes:P roteins
with More Than One Job
r New discussiono f sugar analogs as drugs that
target viral neuraminidase( Chapter 7) New section on the role of transcriptionf actors
(PPARs) in regulation of lipid catabolism
r New material on green fluorescent protein
(Chapter1 7)
(Chapter9 )
Reviseda nd updated section on fatty acid
r New sectiono n lipidomics (Chapter1 0)
synthase, including new structural information
r w descriptionso f volatile lipids used as signals on FASI (Chapter2 1)
vi
Preface tx
Updatedc overageo f
the nitrogen cycle,
includingn ew Box
22-1, UnusualL ife
Styleso f the Obscure
but Abundant,
discussinga nammox
bacteria (Chapter22-
New Box 24-2,
EpigeneticsN, ucleosome
Structure,a nd Histone
Variantsd escribingt he
role of histone
modification and
FIGUR2E1- 3Thes tructuroef fattya cids ynthastyep eI systems.
nucleosome deposition
in the transmissiono f
epigeneticin formation in heredity New information on the roles of RNA
in protein biosynthesis
New information on the initiation of replication
(Chapter 27)
and the dymamicsa t the replication fork,
introducing AAA+ ATPases and their functions New section on riboswitches
in replication and other aspectso f DNA (Chapter2 8)
metabolism( Chapter2 5)
New Box 28-1, Of Fins,W hgs, Beaks,a nd Things,
New section on the expandedu nderstandingo f describingt he cormectionsb etweene volution
the roles of RNA in cells (Chapter 26) and development
BiochemiMcael thods
An appreciation of biochemistry often Glutathione
(GSH)
requires an understanding of how bio-
chemical information is obtained. Some
G€ne for tusion prctein
of the new methodso r updatesd escribed I
in this editiona re: flcuflt9 -12 The useo f taggedp roteinsi n protein purifi- v
cation. The use of a CST tag is illustrated( a) Clu-
tathione-s-transfera(sCeS T)i s a smalle nzyme( depicted Express tu8ion
r Circulard icluoism (Chapter4 ) hereb y the purplei con)t hatb indsg lutathion(ea S luta- Foteh h a cell
mater esidueto whicha Cys-Clyd ipeptideis a ttacheda t
r Measuremento f glycated thec arboxycl arbono f theC lu sidec hain,h encet hea b-
hemoglobina s an indicator of breviationC SH) (b) The CSTt ag is fusedt o the catr
averageb loodg lucosec oncentration, boxyl terminus of the target protein by Senetic
engineeringT he taggedp roteini s expressedin host
overd ays,i n personsw ith diabetes cells,a nd is presenitn the crudee xtracwt hent he cells
(Chapter7 ) are lysed The extract is subjectedt o chromatography Add gotein
on a columnc ontaininga mediumw ith immobilized
r Useo f MALDI-MSi n determinationo f SlutathioneT he CsT{aggedp roteinb indst o the 8lu-
tathione,r etardinBit s migrationt hrought he column,
oligosaccharidset ructure (Chapter7 ) while the other proteinsw ash throughr apidly The
taggedp roteini s subsequentelyl utedf rom the column
r ForensicD NA analysisa, majoru pdate
with a solutionc ontaininge levateds altc oncentratioonr
coveringm odernS TRa nalysis( Chap- free glutathione
ter 9)
r More on microarrays( Chapter9 )
r Use of tags for protein analysisa nd
purification (Chapter9 )
EIub fusion plobin
r PET combinedw ith
IIGUR9E- 12
CT scanst o pinpoint cancer
(Chapter1 4) r Developmento f bacterials trainsw ith alteredg e
r Chromatini mmunoprecipitationa nd ChlP-chip netic codes,f or site-specifici nsertion of novel
experiments( Chapter2 4) amino acids into proteins (Chapter 27)
-
x Preface
MedicalRlye levaEntx amples
This icon is usedt hroughoutt he book to denote r Box 15-3, GeneticM utationsT hat Leadt o Rare
materialo f specialm edicali nterest.A s teachers, Formso f Diabetes
our goal is for studentst o learn biochemistrya nd to
r Mutationsi n citric acid cycle enzyrnest hat lead to
understand its relevance to a healthier life and a cancer( Chapter1 6)
healthier planet. We have included many new exam-
r Perniciousa nemiaa nd associatedp roblemsi n strict
ples that relateb iochemistryt o medicinea nd to health
vegetarians( Chapter 18)
issuesi n general.S omeo f the medicala pplicationsn ew
to this edition are: r Updatedi nformationo n cyclooxygenasheh ibitors
(pain relieversV ioxx, Celebrex,B extra)
r The role of polyunsaturatedf atty acidsa nd trans
(Chapter2 1)
fatty acidsi n cardiovasculadri sease( Chapter1 0)
r HMG-CoAr eductase( Chapter2 1) and Box 21-3,
r G protein-coupledr eceptors( GCPRs)a nd the
The Lipid Hypothesisa nd the Developmento f
range of diseasesfo r which drugs targeted to
Statins
GPCRsa re beingu sedo r developed( Chapter1 2)
r Box 24-1, CuringD iseaseb y Inhibiting
r G proterns,t he regulationo f GTPasea ctivity,
Topoisomerasesd,e scribingt he use of
and the medicalc onsequenceosf defectiveG protein
topoisomerasein hibitors in the treatment
function( Chapter1 2),i ncludingn ew Box 12-2,
of bacterial rnfectionsa nd cancer,i ncluding
G Proteins:B inary Switchesi n Health and Disease material on ciprofloxacin (the antibiotic effective
r Box 12-5,D evelopmenot f ProteinK inaseI nhibitors for anthrax)
for CancerT leatment
r Box 14-1,H tghR ateo f Glycolysisin Tlmors Suggests
Targetsf or Chemotherapya nd FacrlitatesD iagnosis
SpeciTahl emeU:n derstandMinegta bolisthmroug0hb esitayn dD iabetes
Obesity and its medical consequences-cardiovascu-
lar diseasea nd diabetes-are fast becominge pidemic
in the industrializedw orld, and we include new mate-
rial on the biochemicalc onnectionsb etween obesity
and health throughout this edition. Our focus on dia-
@
betes provides an integrating theme throughout the Fat synthesie
Fatty acid oxidatioD and storage and storage Fatty acid oxidati
chapterso n metabolisma nd its control, and this will, Stawation response Adipokineproduction Themogenesis
we hope, inspire some students to find solutionsf or
this disease.S ome of the sectionsa nd boxes that
highlight the interplay of metabolism, obesity, and
diabetesa re:
r Untreated DiabetesP roducesL ife-ThreatenineA ci
dosis( Chapter2 )
r Box 7-1 , Blood GlucoseM easurementsin the
Diagnosisa nd T?eatmento f Diabetes,i ntroducing
hemoglobing lycation and AGEs and
FIGUR2E3- 42
their role in the pathologyo f advancedd iabetes
r Box 11-2,D efectiveG lucosea nd WaterT ?ansport r AdiposeT issueG eneratesG lycerol3 -phosphate
in TWoF ormso f Diabetes by Glyceroneogenesi(sC hapter2 1)
r GlucoseU ptakeI s Deficienti n T}pe 1 DiabetesM el r DiabetesM ellitus Arises from Defectsi n Insulin
Iitus (Chapter1 4) Productiono r Action (Chapter2 3)
r KetoneB odiesA re Overproducedin Diabetesa nd r Section2 3.4,O besitya nd the Regulationo f Body
during Starvation (Chapter 17)
Mass,d iscussesth e role of adiponectina nd insulin
r SomeM utationsi n MitochondriaGl enomesC ause sensitivity and tlpe 2 diabetes
Disease( Chapter1 9)
r Section2 3.5,O besity,t he MetabolicS ;'ndrome,a nd
r DiabetesC an Resultf rom Defectsi n the Mitochon T\pe 2 Diabetes,i ncludesa discussiono f managing
dria ofPancreaticB Cells( Chapter1 9) type 2 diabetesw ith exercise,d iet, and medication
AdvanciensT eachinBgio chemistry
f WORKEEDX AMP1IIl -3 EnergeticsofPumping
bYS YnPort
Revisingtl us textbooki s neverj ust an updatinge xerciseA. t Ieasta sm uch time
Cahulal,e lhe maimm .l'g: lum-s-e=l i, mtio that can be
is spent reexaminingh ow the core topics of biochemrstrya re presented.W e lglucosejour
achieved by the plasma membrme Na*-glucose sym-
haver evisede achc hapterw ith an eyet o helpings tudentsl earn and mastert he porter of an epithelial cell, when [Na-]6 is 12 mM,
fundamentalso f biochemistryS. tudentse ncounteringb iochemistryf or the first [(Ninasti]d.e"1 neisg a1t4iv5e )r,o , antdh eth em etemmbprmerea turpeo teins t3ia7l 'Cis -50 mV
trmeo ften haved ifflcultyw ith two key aspectso f the course:a pproachingq uan-
Soltrtion: Using Equation 11-4 (p 396), we can calcu-
titative problemsa nd drawingo n what they learnedi n orgarucc hemistryt o help late the energy inherent in an electrochemical Na+
gradient-that is, the cost of moving one Na- ion up
them understandb iochemistry.T hose sames tudents must also learn a com- this gradientl
plex languagew, ith conventionsth at are oftenu nstated.W eh avem ades ome AG' _. R?lnry+ +z r a,r,
tNal,"
major changesin the book to help studentsc opew ith all these challenges:
We then substitute standardv aluesf or-&, ?, and J, and
new problem-solvingt ools, a focus on organic chemistry foundations, and the given valuesf or [Na-] (expresseda s molar concen-
highlightedk ey conventions. trations), +l for Z (because Na+ has a positive
charge), md 0 050 V for a,y' Note that the membrane
potential is -50 mV (inside negative),s o the chmge in
potential when m ion moves from inside to outside is
50 mV.
NewP roblem-5olTvoinogls
AGt : (8 315J /mol K)(3to rcm 11 4.52 xx t1o0 -2'
r New in-text Worked Examples help studentsi mprove their + 1(96,50J0V .mol)(0 050V )
quantitativep roblem-solvings kills, taking them through someo f the = 112 kJ/mol
This AGr is the potential energyp er mole of Na- in the
most difficult equations. Na* $adient that is available to pmp glucose Given
that two Na- ions passd om their electrochemicagl ra-
r More than 100 new end-of-chapter problems give students dient md into the cell for each glucose canied in by
further opportunity to practice what they have learned. slmport, the energya vailablet o pmp 1 mol of Llucose
is2 x II2 kJ/mol = 22 4 kJ/mol We can now calculate
r New Data Analysis Problems (one at the end of eachc hapter), con tbhye t hciosn pcmenpt ra(ftrioonmr a Etiqou oaft iEolnu lc1o-s3e, t hpa 3t 9cm6) :be achieved
tributed by BrianW hite of the Universityo f Massachusetts-Bostoenn, lG_, = f_t_?.ln :i[-glucose]r
courages tudentst o slmthesizew hat they have learned and apply their Lgrucoselour
Remnuing, then substitutingt he valueso f AGt,,&,a nd
knowledgeto the interpretationo f dataf rom the literature. ?, gives
.'n li[rg"]ou"c"lo.,s,e l* nA,Gr , = E:rs 2.l2lo.4rokJt' t/<mu os llo{(, - o ot
Focuosn 0 rgan(ich emistFryo undations lglucosel,.
-
lglucose]""t
r New Section 13.2, Chemical logic and common biochemical
reactions, discussest he common biochemical reaction types that WORKEEDX AMP1L1E- 3
underlie all metabolic reactions.
r Chemical logic is reinforcedi n the discussionos f
centralm etabolicp athways. cHooPoi
t-
r Mechanism figures feature step-by-step NS' G3-tpycheorsapldheahEyde NS* nH,CtO"Hb
descriptionst o help studentsu nderstandt he Glycerddehyd€ \e ,
reactionp rocess. 3-phosphah CF FsuobdFaatimte @onf pelterxz Fe.fre cvs
dive.sik C)€ ha! e
r Iwne t hceo npsreissteennttalyut ioseno a f sreeat ocft icoonn vmeenctihoannsisms, doeffufdi oc 8lea) dbisw hine fpnotf hm, eN A(E5Do +5re i inE€br ebaaudd4ive, 6v l LI alsPbu UokbvPrsya h.loma ftf teho m emt hdsci oy bthhsHe ereen -Ssieni-ndeu tai€hl€
introduceda nd explainedi n detail with the "N-A\n l ctu-" OPO-?
first enzymem echanisme ncountered uY!c94OH
(chymotrypsin,p p. 208-209).S omeo f ftrhek ag@o alebnett uemth iqbthre SI
suhEaE sd €nzFe I
the new problems focus on chemical u(sdthecske by 4p)h 6rpehledaosbirEyis cv"
mechanismsa nd reinforcem echanisticth emes. flr,eg -bsbep@hdnpdh qplyd@udm,e ^L I Tinhtee m€nezrd€aiuabtestt uoddileadhby
\tl tuNs*boudbse
c1H-"_oP'o"'-o
Key(o nventions Ns, Hcc.:o/or/'o.'P\ OH - P.ND+ NsH HCCOHH,OPO:
C:O
In this edition, many of the conventionst hat are so
S
necessaryf or understandinge ach biochemicalt opic CF far€ ctivNe0 sHik updr cdisu crte plelaacveeds bftye cvg
another nolecule of NS+.
and the biochemicall iterature are broken out of the
text and highlighted. These Key Conventions FIGUR14E- 7
include clear statementso f many assumptionsa nd
conventionst hat studentsa re often expectedt o assimilatew ithout KtY (0NVENTI0NW: hen an amino acid sequenceo f a
being told (for example,p eptide sequencesa re uritten from amino- peptide, polypeptide,o r protern is displayed,t he amino-
to carboxyl-terminale nd, Ieft to right; nucleotide sequencesa re terminal end is placed on the left, the caxboxyl-terminal
end on the right The sequencei s read left to dght, be-
writtenf rom5 ' to 3' end left1 nr ioht) giming with the amino-terminal end I