Chapt er14-Al l ost er y Tr ue/ Fal seandMul t i pl eChoi ce( 7) 1)
Whi choft hef ol l owi ngcanr esul ti nanal l ost er i cm mo odul at i onofact i vi t y: a)coval entmodi ficat i onsuchasphosphor yl at i onoracet yl at i on b)ol i gomer i zat i on c)bi ndi ngofal i gand d)s t abi l i zi nganal t er nat i v ec onf or mat i on e )al loft heabov e
2) Thet r anscr i pt i onofagenei scont r ol l edbyat r anscr i pt i onf act orbi ndi ngei t her Gl ucoseorLact ose.Whent her ei s0. 2mM ofei t herGl ucoseorLact osei nt hecel l , t hegenei st r anscr i bedatabout10% oft hemaxi mum. m.Wh Whent her emo mor et han2mM mM Gl ucosei nt hecel l ,t hegenei sf ul l yi nduced.However ,whent her ei s2mM Lact ose i nt hecel l ,t her eamountoft r anscr i pt i oni sappr oxi mat el yhal foft hemaxi mum.At 40mM ofei t herGl ucoseorLact osei nt hecel l ,t hegenei sf ul l yi nduced.The t r anscr i pt i onalr egul at i oni sl i kel y: a)ul t r asensi t i vewi t hr espectt obot hGl ucoseandLact ose b)ul t r asensi t i vewi t hr espectt oLact osebutnotGl ucose c)gr adedwi t hr espectt oGl Gl ucose d) ul t r a se ns i t i v ewi t hr e spe ctt oGl uc os ebutnotLa ct os e
e)hyper bol i cwi t hr espectt oGl ucosebutnotLact ose 3)
I nal l ost er i cpr ot ei ns,l i gandbi ndi ngcanonl yr esul ti nposi t i vecooper at i vi t y True/ Fal s e
4)
Whi choft hef ol l owi ngi snotaknownal l ost er i ceffect orofhemogl obi n: a)oxygen b)bi sphosphaogl ycer at e c)l owpH d)my myogl obi n
e)CO2 5)
Bact er i alchemo mot axi si nvol vesonl yr andom m, ,br owni anmoveme ment True/ Fal s e
6) Becauseoft hei mpor t anceoft heFhel i xi noxygenbi ndi ng,t heal l ost er i c hemogl obi npr ot ei nsofal lor gani smsar et et r amer i cassembl i es True/ Fal s e 7)
Whi choft hef ol l owi ngst at ement saboutt heHi l lcoeffici entar et r ue: i .i ti st hest eepnes soft hel ogl ogbi ndi ngi sot her m att hehal fs at ur at i onpoi nt i i .al l os t er i cs ys t emshav eaHi l lc oeffic i entofex ac t l y1 i i i . t hemax i mum v al uef oradi mer i cpr ot ei ni s2 a)onl yi b)iandi i i
c)i iandi i i d)al loft hes t at ement sar et r ue Fi l li nt heBl ank( 5) 1)Whenasyst em i sul t r asensi t i ve,t her esponset oani nputi s_______t hanexpect ed f r om t hegr aded,hyper bol i cr esponse. ( s h a r p e r )
2)
Oxygenbi asest heequi l i br i um ofhemogl obi nt owar dst he_____st at e ( Rorr e l a xe d)
3) Theext entofflagel l arcl ockwi ser ot at i oni sgover nedbyt he ___________________oft hepr ot ei nCheY ( phos phor y l a t i on) 4) The__________hi st i di ner esi dueofhemogl obi nsenset heeffect i vesi zeoft he hemei r onat om ( pr oxi ma l )
5) Aneffectofcol ocal i zat i oni st ogr eat l yi ncr easet hel ocal__________oft wo p r o t e i n s ( c onc ent r a t i on) LongAnswer / Essay( 12)
1) Adi mer i cgl ucoki nasehasabi ndi ngsi t ef orgl ucosei neachsubuni t .TheKD f or t hefir stbi ndi ngeventi s1mM andt heKD f ort hesecondeventi s10uM.a)Whati s t heHi l lc oeffici ent ?b)I st hi spr ot ei npos i t i v eornegat i v el ycooper at i v ewi t hr es pec tt o gl ucosebi ndi ng? Answer :
a) nh =2/( 1+√( K / ) D2KD1) =2/( 1+√( 0. 01/ 1) ) =1. 8 b) nh>1,t her ef or ei ti sposi t i v el ycooper at i v e 2) Adi mer i chemogl obi ni si sol at edf r om afish.Eachsubuni tcont ai nsabi ndi ng si t ef oraXenongasmol ecul e.TheKD f ort hefir stbi ndi ngeventi smeasur edat 23nM.TheKD f ort hesecondbi ndi ngeventi smeasur edat3. 5uM.a)Whati st heHi l l c oeffic i ent ? b)I st hi spr ot ei npos i t i v eornegat i v el yc ooper at i v ewi t hr es pec tt oXenon bi ndi ng? Answer :
a) nh =2/( 1+√( K / ) D2KD1) =2/( 1+√( 3. 5/ 0. 023) ) =0. 15 b) nh<1,t her ef or ei ti snegat i v el ycooper at i v e 3) Adi mer i cenzymewi t ht woi dent i calbi ndi ngsi t eshasaHi l lcoefficentof1. 3.I f t heKD oft hefi r s tbi ndi ngs i t ei s200nM,whati st heKD oft hesecondbi ndi ngsi t e? Answer : 2 KD2=KD1x( 2/ nh-1) =200x( 2/ 1. 31)2 =58nM
/ ( 1f ) 4) Whati st her at i oofboundt ounboundr ecept or(f )f oradi mer i cpr ot ei nwi t h t wobi ndi ngs i t es( KD1 =20nM,KD2 =2nM)at15nM concent r at i onofl i gand?
Answer : f / ( 1f )=( [ L] / KD1 +( [ L] / KD1) *( [ L] / KD2) ) / ( 1+[ L] / KD1)
=( 15/ 20+( 15/ 20) *( 15/ 2) ) / ( 1+15/ 20) =3. 64 5) Adi mer i cal l ost er i cpr ot ei ni si sol at ed.Asci ent i stmeasur est heKD1 f ort hefir st bi ndi ngsi t eat25nM andt heHi l lcoeffici entas1. 6.a)Whatf r act i onoft hepr ot ei ni s boundat10nM concent r at i onofl i gand?b)Asi ngl epoi ntmut at i onabol i shesal l c ooper at i v i t yi nt hepr ot ei ns uc ht hatt hepr ot ei nbi ndsi t sl i gandwi t hanappar entKD equalt o25nM.Whati st hef r act i onoft hepr ot ei ni sboundat10nM concent r at i onof l i g a n d ? Answer : a) 2 KD2=KD1x( 2/ nh-1) 2 =25x( 2/ 1. 9-1) =1. 56nM f / ( 1f )=( [ L] / KD1 +( [ L] / KD1) *( [ L] / KD2) ) / ( 1+[ L] / KD1) =( 10/ 25+( 10/ 25) *( 10/ 1. 56) ) / ( 1+10/ 25) =2. 12 f=2. 12-2. 12f 3. 12f=2. 12 f=2. 12/ 3. 12 f=. 68
b) f / ( 1f )=[ L] / KD
=10/ 25 =0. 4 f=0. 4/ 1. 4 =0. 29 6) Thefir standsecondbi ndi ngsi t esofaposi t i vel ycooper at i veal l ost er i cdi mer i c pr ot ei nhaveKDsof100mM and10uM r espect i vel y .a)Sket cht hebi ndi ngi sot her ms ofl og( f / ( 1f ) )v sl og( [ L] )b)Whati st heHi l lcoeffici ent ?
Answer : a)
b)
nh =2/( 1+√( K / ) D2KD1) 5 =2/( 1+√( 10 / 10-1) ) =1. 98 7) Thefir standsecondbi ndi ngsi t esofanegat i vel ycooper at i veal l ost er i cdi mer i c pr ot ei nhaveKDsof100uM and10mM r espect i vel y .a)Sket cht hebi ndi ngi sot her ms l og( f / ( 1f ) )v sl og( [ L] )b)Whati st heHi l lcoeffici ent ? Answer : a)
b) nh =2/( 1+√( K / ) D2KD1) 2 4 =2/( 1+√( 10 / 10 ) ) =0. 18
8) Twohomol ogsofapr ot ei nar ei sol at ed.Homol ogAi samonomert hatbi nds gl ucosewi t haKD of4mM.Homol ogBi saposi t i vel ycooper at i vedi mer .TheKD of t hefir stbi ndi ngsi t eofHomol ogBi smeasur edat4mM.At1mM concent r at i onof gl ucose,i ti sf oundt hatHomol ogBbi ndst wi ceasmuchgl ucoseashomol ogA. Whati st heHi l lcoeffici entofHomol ogB? Answer :
Forhomol ogA: f / ( 1f )=[ L] / KD =1/ 4=0. 25 Si ncehomol ogB,bi ndst wi ceasmuchgl ucose,f / ( 1f )=0. 5 f / ( 1f )=0. 5=( [ L] / KD1 +( [ L] / KD1) *( [ L] / KD2) ) / ( 1+[ L] / KD1) 0. 5=( 1/ 4+( 1/ 4) *( 1/ KD2) ) / ( 1+1/ 4)=( 0. 25+0. 25*( 1/ KD2) ) / ( 1. 25) KD2 =0. 67mM nh =2/( 1+√( 0. 67/ 4) ) =1.41 9) Acycl i sti si nt er est edi ncheat i ngi nar acebydel i ver i ngmor eoxygent ohi s muscl es.Thecycl i str easonst hatsi nceBi sphosphogl ycer at e( BPG)st abi l i zest he“ T” st at eofhemogl obi n,whi chr educesaffini t yf oroxygen,t hatr educi ngt heBPG concent r at i oni nhi sbl oodcel l sshoul dbegoodf orhi sper f or mance.Howmi ght r emovi ngBPGmi ghthaveadet r i ment aleffectondel i ver yofoxygent ohi smuscl es? Answer :
BPG act sasanal l ost er i ceffect orf orhemogl obi n.RemovalofBPG wi l lr esul ti na shar perswi t chbet weensat ur at edandempt yhemogl obi n.WI t houtt hi seffect , t hebi ndi ngi sot her m wi l lnotmat cht hedi ffer encei noxygenconcent r at i on bet weent hear t er i alandvenousbl oodandl i kel yl eadt osubopt i maldel i ver yof oxygent ohi smuscl es.
10) Duet oaf asci nat i ngcoupl i ngbet weenf ol di ngandl i gandbi ndi ng,t hedi mer i c acet ylt r ansf er aseenzymeAACdi spl aysposi t i vecooper at i vi t yatl owt emper at ur es andnegat i vecooper at i vi t yathi ght emper at ur es.At10C,AAChasaKD1 =330uM and KD2 =130uM.At37C,AAChasaKD1 =200uM,KD2 =230uM.a)Whati st heHi l l coeffici entateacht emper at ur e?b)Whati st hechangei nf r act i onboundat50uM l i gandbet ween10and37C?
( Sour ce:Fr i ebur geretal ,NSMB,2011;Affini t i eshavebeenal t er ed) . Answer : a)
For10C: nh =2/( 1+√( K / ) D2KD1) =2/( 1+√( 130/ 330) ) =1.23 For37C: nh =2/( 1+√( K / ) D2KD1) nh =2/( 1+√( 230/ 200) ) =0. 97 b)
For10C f / ( 1f )=( [ L] / KD1 +( [ L] / KD1) *( [ L] / KD2) ) / ( 1+[ L] / KD1) =( 50/ 330+( 50/ 330) *( 50/ 130) ) / ( 1+50/ 330) =0. 18 f=0. 18/ 1. 18 =0. 15 For37C f / ( 1f )=( [ L] / KD1 +( [ L] / KD1) *( [ L] / KD2) ) / ( 1+[ L] / KD1) =( 50/ 200+( 50/ 200) *( 50/ 230) ) / ( 1+50/ 200) =0. 24 f=0. 24/ 1. 24 =0. 19 Thus,4% mor eenzymesar eboundatt hehi ghert emper at ur e.Event hough AACi snegat i vel ycooper at i veathi ghert emper at ur es,mor eoft hepr ot ei ni s boundt ol i gand.Thi si sdr i venbyt hef avour abl echangei nKD1athi gher t emper at ur es. 11) HowdoesCO2 di r ect l yandi ndi r ect l yst abi l i zet he“ T”st at eofhemogl obi ni n venousbl ood? Answer :
CO2 di r ec t l ys t abi l i z est he“ T”s t at ebyr eac t i ngwi t ht heNt er mi nalami nogr oups oft hepr ot ei n.Thi sal t er st hei nt er f ac i ali nt er ac t i onsbet weent heal phaandbet a
subuni t s,st abi l i zi ngt he“ T”st at er el at i v et ot he“ R”s t at e.CO2 i ndi r ect l y s t abi l i z est he“ T”s t at ebyr educ i ngt hepHwi t hi nr edbl oodc el l s .Ther educ t i on i npH l eadst ot heBohreffectwher ebet asubuni tHi s146becomespr ot onat ed. Thi sdi sr upt si nt er act i onscent r edar oundt hei onpai rwi t hbet aAsp94andan i nt er ac t i ont oal phaL ys40.Wi t houtt hes ei nt er act i ons,t he“ T”s t at ei sst abi l i zed.
12) Twopr ot ei nsar emodi fiedbymyr i st oyl at i on,whi cht ar get st hem t ot hepl asma membr anei nacel lat25C.Thi schangest hei reffect i vel ocalconcent r at i onf r om 10nM t o1uM.Assumi ngt hatanyf avour abl emut at i onwoul di ncr easet hei r i nt er act i onener gyby4kJ/ mol.How manyf avour abl emut at i onswoul dhavet ooccur i nt heabs enc eofc ol oc al i z at i ont or es ul ti nanequi v al enteffec t i v eaffini t yas obser vedwhent het wopr ot ei nsar ecol ocal i zed? Answer : 8
8
6
6
n( 10 x10 ) / ( 10 x10 )=2. 5*l n( 0. 001)=23kJ/ mol ∆∆G =RTl I feachmut at i onadded4kJ/ mol ,t heatl east6mut at i onswoul dber equi r edt o r esul ti nashi ghaneffect i veaffini t y. 13) Asci ent i stfindst wopat hways,dependentondi st i nctki naseact i vi t i es,whi ch act i vat east r essr esponsei nyeast .Onepat hwayr espondst oel evat edl evel sofsal t andt heot herr espondst oel evat edl evel sofcaffei ne.Bot hpat hwaysr esul ti n t r ans cr i pt i onoft hec haper oneHs p90.Bel owi sat abl el i s t i ngt her el at i v e concent r at i onsofsal torcaffei neandt hemeasur edt r anscr i pt i onofHsp90.Expl ai n whi chpat hwayl i kel ycont ai nsasi ngl eki naseandwhi chpat hwayl i kel ycont ai nsa ki nasecascadesi mi l art ot heMAPki nasepat hway
[ NaCl ]mM
Hsp90t r anscr i pt i on
1
0
2
1
3
1
4
40
[ NaCl ]mM
Hsp90t r anscr i pt i on
1
0
5
100
10
100
100
100
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100
[ caffei ne]mM
Hsp90t r anscr i pt i on
1
0
2
0
3
1
4
1. 1
5
2
10
10
100
50
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100
Answer :
Onl yt hes al tr es pons ei sul t r as ens i t i v e( i nt hati tunder goesac ompl et eac t i v at i on i na~2f ol dr at hert han~100f ol dconc ent r at i onchange) .Ul t r asens i t i v i t y r es ul t i ngf r om t hec oupl i ngofmul t i pl ek i nas esconv er t sagr adedi nputs i gnali nt o as har ps wi t c h.Thi ssi t uat i oni sobs er v edonl yf ort hes al tr es pons e,whi c hl i k el y hasaki nasecascade,andnotf ort hecaffei ner esponse,whi chi smor e hy per bol i c .
