a supernova in 1572. The Cassiopeia-911 beamline [15] is a uni que facility with Щve experimental stati ons at one beamline. It is the result of a collaborati on ...
V ol . 1 0 1 ( 2002)
A CT A P HY SIC A P O LO N IC A A
No . 5
P r oceedi ng s o f t h e Sy m p o siu m o n Syn chr otr on Cr y st all ogr ap hy, Kr y n ica, Po l an d 200 1
D esi gn of a 5-Station Ma cro m olecu lar C r y stallogra p hy B eam lin e at M A X- L ab C.B. M ammen a , T. U r sby b , Y . Cere n ius b ;c , M. T hun nis sen c , J. A l s-N iel sen a , S. La rs en d and A . Li l ja s b a
Ni els Bo h r I nsti t ute,
â
rste d L abo rato r y, Uni versi ty of Cop enhagen
Uni versi tetspa rken 5, 2100 Co penha gen, Denm ark b c
M A X -l ab, Lund Uni versi ty , P.O. Bo x 118, 221 00 Lund, Sweden
Mo l ecul ar Bi ophysi cs, Center for Chem i stry and Chem ical Eng i neeri ng Lund Uni versi ty , P.O. Bo x 124, 221 00 Lund, Sweden d
Centre for Crysta l l ogra phi c Studi es, D epartm ent of Chem i stry Uni versi ty of Cop enhagen Uni versi tetspa rken 5, 2100 Co penha gen, Denm ark
A beam l ine for ma cromolec ular cr y stallo gra phy is un der construction at the Swedish synchrotron light source MA X - lab at Lund U niversity in a collab ora tiv e e˜ort b etw een Denmar k and Sw eden. Of the 7 mrad hori zontal w iggler fan emitted from the new superconducti ng multip ole wiggler , the central 2 mrad will be used and split in three parts. T he central 1 mrad w ill be used for a tunable station optimised for multi- wavelength anomalous di˜racti on exp eriments and on each side of the central fan there w ill b e tw o Ùxed wavelength stations using di˜erent energies of the same part of the beam. T hese in total Ùve stations can be used simultaneousl y and indep end ently for collecti ng di˜ractio n data. PACS numb ers: 07. 85.Qe, 87. 14. Ee, 87. 14. Gg
1. I n t r o d u ct io n A three- di m ensiona l m odel of a pro tei n at the ato mi c l evel pro vi des a weal th of i nf orm ati on. In addi ti on to showi ng the o veral l fol di ng to p ol ogy, i t pro vi des the ba sis for a deta i l ed understa ndi ng of i ts bi ol ogi cal functi on [1]. X- ra y crysta l logra phy pl ays a centra l ro l e i n the developm ent o f structura l bi ol ogy, as the maj or exp eri menta l metho d for determ i ni ng hi gh- resol uti on mo dels of macro molecul es [2, 3]. The ra pi d gro wth of determ ined bi ol ogi cal m acromolecul ar structures [2] and the expected accelerated growth due to the advent of structura l g enom i cs pro j ects (5 95)
596
C.B. M amm en et al .
[4] are exp ected to ha ve a l arg e i m pact on e.g. pha rm aceuti cal developm ent [5, 6]. Ano ther exampl e of the techno logi cal i nterest i n structura l bi ol ogy i s the p otenti al i m p orta nce of hi gh- resol uti on structura l determ i nati ons for the developm ent of enzym es wi th new pro perti es [7]. X- ra y synchro tro n ra di ati on pro vi des m any adv anta ges compa red to conventi ona l X- ra y sources, due to i ts hi gh i ntensi ty and hi ghl y coll i m ated ra di ati o n wi th wavel ength tuna bi l i ty , i ncreasing the accura cy and ease of structure determ ina ti ons and extendi ng the appl i cabi l i t y of X- ra y crysta l l ogra phy to m ore di £ cul t pro j ects tha t are often al so the more i nteresti ng ones. The use of synchro tro n radi ati o n ha s pl ayed a funda menta l ro le i n the possibi l i ty to ta ckl e more di £ cul t pro bl ems as wel l as i n the i ncreased structure determ i na ti on rate [8]. Mo re tha n 90% of the publ i cati ons i n m acrom olecular crysta l l ogra phy i n 2000 were based on m easurem ents wi th synchro tro n ra di ati on [9]. Pro gress i n m ol ecular bi ol ogy and com puta ti ona l techni ques together wi th the i ncreased a vai labi li t y of dedi cated synchro tro n beaml i nes ha s contri buted to a ra pi dl y i ncreased use of the multi - wavelength ano mal ous di ˜ra cti o n (MAD ) techni que for structure determ i nati ons [10]. In a MAD exp eri ment da ta i s col l ected at several wa velengths aro und an absorpti on edge of one of the elements i n the macro m ol ecule. By expl oi ti ng the ano malo us scatteri ng the so-call ed crysta l l ogra phi c pha se pro bl em can b e sol ved and com pl ete structura l model s b e determ i ned. In a m aj ori ty of the cases Se i n the form of Se-m ethi o ni ne i s the ano mal ous scatterer wi th i ts K absorpti on edge at 0 .98 ¡A (1 2.7 keV). The MAD techni que al so ho lds the pro m i se of b eing suita bl e fo r the i ncreased thro ugh- put desired by structura l genom i cs pro j ects [11] tho ug h the sing l e-wa velength ano m alous di ˜ra cti on (SAD ) techni que m i ght pro ve mo re suita bl e i n som e cases [12]. In SAD experi m ents the ano m alous signa l i s used as in MAD exp eri ments but data i s col l ected at onl y one wa vel ength, chosen to opti mi se the anom al ous signal . The dem and for synchro tro n b eam ti m e i s no t onl y rel ated to the possibi l i ty of expl oi ti ng the wa velength tuna bi l i ty requi red by MAD and SAD experi m ents, but also to a l arge extent due to the i mpro ved da ta qual i ty at synchro tro n b eam l i nes com pared wi th l ab orato ry sources. La rg e structures such as vi ruses and l arge cell ul ar com pl exes are exampl es where synchro tro n b eam ti m e i s a necessity , but thi s i s true al so in man y other cases. Structure determ i na ti ons of p otenti al drug ta rg ets i n com pl exes wi th drug candi da tes i s one exampl e where abunda nt b eam ti m e wi th ra pi d access can pl ay a cruci al rol e. In order to do m easurem ents wi th synchro tro n radi ati on one ha s to appl y for b eam ti m e well i n adv ance a t one of the avai l able synchro tro n l i ght sources aro und the worl d. The b eam ti me avai la ble i s not su£ cient to m eet the i ncreasing dem ands caused by the ra pi d gro wth o f structura l bi ol ogy. The MAX I I synchro tro n ra di ati on facil i t y at MAX- l ab, Lund, i s a 1.5 G eV stora ge ri ng [13] wi th ei ght stra i ght secti ons for i nserti on devi ces tha t can o perate up into the hard X- ra y regi m e. It i s theref ore a very attra cti ve resource for researchers i n bi o-crysta l l ogra ph y. The
Desi gn of a 5- Stati on Macromol ecul ar Cr ystal l ogr aphy
.. .
597
purp ose of the here descri b ed b eam li ne i s to further expl oi t thi s p otenti al by i ncreasing the av ail abl e b eam ti me and to extend the capacity to MAD and SAD exp eri ments. The onl y crysta l l ogra phy b eam l i ne i n Scandi na vi a so f ar, I7 11 at MAX- l ab [14], i s onl y partl y dedi cated to ma cromol ecular crysta l l ogra phy and i s onl y slowl y tuna bl e m aki ng i t no n- suita bl e for MAD experi m ents. The b eam l ine ha s b een na med Cassiop eia after the Ùve-sta r constel la ti on where the Dani sh astro no m er Tycho Bra he, l i vi ng no t far f rom Lund, di scovered a superno va i n 1572. The Cassio peia -911 b eam l i ne [15] i s a uni que facil i ty wi th Ùve exp eri menta l sta ti ons at one b eam l ine. It i s the resul t of a col l abo rati on b etween D ani sh and Swedi sh researchers i n the â resund regi on, fro m Lund and Co penha gen Uni versi ty . The econom i cal ba sis for the constructi on of the b eam l i ne com es fro m a grant to the Departm ent of Mo lecula r Bi ophysi cs, Lund Uni versi ty , fro m the Knut and Al i ce Wal lenb erg Founda ti on, a gra nt to the Centre for Crysta l l ogra phi c Studi es, Uni versi ty of Cop enhagen, fro m The D ani sh Bi otechno l ogy Instrum ent Center and fro m a consorti um form ed by the two pha rm aceuti cal com pani es Astra Zeneca and No vo No rdi sk A / S. The b eam li ne i s al so supp orted by the Swedish Research Co unci l thro ug h MAX- l ab. 2. T h e n e w M A X -wi g gl er The source fo r the b eam l ine i s a new col d- bore superconducti ng mul ti p ole wi ggl er designed and bui l t at MAX- l ab [16]. Som e pa ra meters descri bi ng the wi ggl er are found i n T abl e I. T ABLE I Some parameters describing the sup ercondu ctin g wiggler. N umb er of poles
49
Wiggle r p erio d Length of w iggler,
L w i gg l er
Peak Ùeld
6.1
mm
1 51 2
mm
3.54
DeÛection parameter, Electron beam energy,
T
21.2
K
1.5
GeV
Electron beam current
250
mA
C ritical energy
5.2
keV
E e
The wi ggl er ra di ati on i s emi tted i n a di verg ent cone as i l l ustra ted i n Fi g. 1. The ho ri zonta l and verti cal o peni ng ang les are g iven by [17]: K =Û =
where
7 m ra d ( h );
Û = E e= m ec
2
, wi th
1= Û m ec
2
=
0: 34 mra d ( v ) ;
(1 )
b eing the el ectro n rest energy (see al so T abl e I). D ue
598
C.B. Mammen et al .
to the typi cal l ength of wi ggl ers in the order of one or a few m eters, the vi rtua l source size i ncreases signi Ùcantl y at l arg e vi ewi ng ang les. Si nce the maxi mum accepta bl e pho to n b eam emi tta nce at the sam pl e i s around 1 mm  mra d, onl y the centra l pa rt of the wi gg ler fan wi l l b e used for the exp eri menta l sta ti ons.
Fig. 1.
Schematic draw ing of the magnetic array of a wiggler w ith its radiation
cone.
Fig. 2.
C omparison of the calculated Ûux from the new MA X -wiggler w ith Ûuxes from
the MA X -lab I 711 wiggler, the ES RF bendin g magnet beamline BM14, and the 9. 6 b eamlin e at SRS Daresbury . T he Ûux is given per horizontal
op ening angle.
The cal cul ated Ûux of the source i s pl otted i n Fi g. 2 and com pared wi th the source Ûux of som e exi sti ng beaml i nes for macro mol ecular crysta l l ogra phy. W a velengths aro und 1 ¡A (1 2.4 keV) are suita bl e for most m acrom ol ecular structure determ i na ti ons tho ug h wa velengths at l onger or shorter wavel engths can b e requi red e.g. for MAD exp eri ments. The ra ng e 0.7{ 1.8 ¡A (7 { 18 keV) covers the requi rem ents of most exp eri ments. The Ûux of the new MAX- wi ggl er i n tha t wavel ength ra nge i s indeed com pa rabl e wi th the shown existi ng b eam l i nes, tho ugh the bri ll i ance of 3 È 1 0 1 5 pho to ns/ (s 0.1% bw m rad 2 m m 2 ) (bw = ba nd wi dth) i s up to Ùve orders of m agnitude inf eri or to undul ator beaml i nes at hi gher- energy stora ge ri ng s such as ESR F [18]. Thi s m eans tha t the Cassiop eia-911 b eaml i ne wi l l ha ve Ûux val ues compa ra bl e to these sources but wi l l no t reach the sam e smal l fo cal spot sizes o r hi gh col li m ati on of the ra di ati on. The to ta l p ower of the wi ggl er i s of the order of 5 kW [16].
Desi gn of a 5- Stati on Macromol ecul ar Cr ystal l ogr aphy
599
.. .
3. Co n cep t of t h e b ea m l i n e The centra l 1 mra d of the ra di a ti on cone, Fi g. 1, wi l l b e used excl usivel y for an energy- tuna bl e stati on, opti m i sed for MAD experi m ents, and the adj acent 0.5 m ra d on each side wi l l b e used for four Ùxed wavel ength side sta ti ons di ˜ra cti ng ho ri zonta l l y away f rom the synchro tro n b eam, as i l l ustra ted i n the \ top vi ew" i n Fi g. 3. The wa velengths of the side sta ti ons are chosen i n part to cover some i m p orta n t absorpti on edges used for SAD experi m ents and i n pa rt to gi ve the hi ghest qual i ty b eam for exp eri ments no t rel ated to ano m alous scatteri ng .
Fig. 3. upstream
T op- view sketch of the di˜erent
exp eriment stations at the beamline. T he tw o
side stations w ill ha ve diamond
mono chromators
(C ) and the tw o dow nÊ
stream side stations silicon mono chromators (Si), all being bent for horizontal A ll side stations
will ha ve multilayer
(ML)
mirrors
focusing.
for vertical focusing. T he central,
energy- tunabl e station w ill ha ve more classical grazing incid ence mirrors and a Si double crystal mono chromator.
T ABLE I I Predicted perf ormance of the side stations. T he mono chromators of the 1.10 ¡A and 0.97 ¡A stations are made of diamonds in the Laue conÙguratio n and the remaining tw o side stations are Si or Ge crystals in the Bragg conÙguration . W avelength
Ñ1
W avelength
Ñ2
W avelength
Ñ3
W avelength
Ñ4
Relative bandw idth,
= 1.10 ¡A ¡ = 1.03 A = 0.91 ¡A ¡ = 0.97 A Â E =E
¤
1
È
10
À
Spot size
0: 3
Flux w ith Laue mono chromator
10
photons /s
Flux w ith Bragg mono chromator
10
photons/s
0 :3
mm
600
C.B. Mammen et al . T ABLE I I I Predicted
perf ormance of the MA D station. = 0.7 ¡A to 1.8 ¡A
W avelength range Relative bandw idth,
 E =E
Sp ot size Flux at 1 ¡A ¡ in Flux at 1 A
0: 1
È
0: 1
mm
¤
2
¤
0: 3
¤
3 5
È
È
10 È
10 10
À
4
0 : 25 12
mm
2
photons/s photons/s
The opti cal com p onents of the beaml i ne wi l l be designed and constructe d accordi ng to the requi rements for macrom olecul ar crysta l l ography . The predi cted chara cteri sti cs of the b eam at the sam pl e p ositi on of the four side sta ti ons are found i n T abl e I I and of the MAD stati on i n Table I I I.
The two upstrea m m ono chromato rs for the side sta ti ons are asym metri c di am ond (1 11) crysta ls i n La ue tra nsm i ssion geom etry (Fi g. 3). D i amond i s chosen due to i ts hi gh tra nsm i ssion ab ove 10 keV i n order to al l ow the extra cti on o f an addi ti ona l do wnstrea m m ono chro m atic b eam. The outer di m ensions of the di am ond crysta l s wi l l be m m , and the crysta l s are bent m eri di ona l ly to pro vi de focusi ng i n the hori zonta l pl ane. Thi s techni que has previ ously b een used wi th sili con crysta l s [19]. Addi ti onal l y, the bendi ng i ncreases the accepted ba nd wi dth by a facto r two . The m eri di ona l b endi ng ra di us o f curv ature wi l l be 12 m to achieve the requi red fo cusing . The fra cture l im i t f or bendi ng of thi n crysta l s i s typi cal l y reached fo r , where i s the crysta l thi ckness [20]. Hence, the requi red bendi ng ra di i for the di amond crysta l s are obta ina bl e. The m onochro mato rs for the do wnstrea m side sta ti ons are Si (1 11) crysta l s i n asym m etri c Bra gg reÛection geom etry . The outer di m ensions are mm and they wi l l al so b e b ent to pro vi de m eri di ona l focusing . The asym metry ang le for the Si crysta l at the 1.03 ¡A sta ti on wi l l b e 2.5 and i ts bendi ng radi us 52 m. The verti cal fo cusing i s obta i ned by curved mul ti lay er mi rro rs i nserted i n the do wnstrea m beam fro m the mono chro mato rs. Mul ti l ayer m irro rs are chosen due to the l arg er ang l e of b eam i nci dence com pa red to conventi onal mi rro rs. Thi s al l ows shorter m irro rs and thus considera bl e cost reducti on. The four m i rro r substra tes are i denti cal : 450 mm l ong , m ade of SiO and p ol i shed to a Ùxed ra di us of curv ature of 400 m . The m ulti layer m ateri als are al terna ti ng Si and Mo wi th a to ta l of 150 bi l ayers. Si nce the angl e of i nci dence vari es al ong the m i rro r, the -spacing i s l ong itudi na l ly gra ded to obta i n Bra gg di ˜ra cti on at b oth ends of the mi rro r simul taneousl y. The multi lay er p eri od and l ong i tudi na l gra di ng i s speciÙed accordi ng to the wavelengths of the i ndi vi dua l four side sta ti ons. The predi cted chara cteri sti cs of the side sta ti ons are found i n Table I I.
Desi gn of a 5- Stati on Macromol ecul ar Cr ystal l ogr aphy 5 . D esi g n o f t h e MAD
.. .
601
st at i o n op t i cs
The opti cs of the MAD sta ti on wi l l consist of a verti cal l y col l im ati ng m i rro r, a doubl e-crysta l Si(1 11) m onochro mato r and a to ro i dal fo cusing m i rro r. A sol uti on where the ho ri zonta l fo cusing i s do ne by the second m i rro r i nstea d of by the second m ono chro m ator crysta l was chosen since i t was bel ieved to gi ve an easier- to -use b eam l ine for the users. The coll i m ati ng m i rro r i s needed to achi eve the hi gh energy resol uti on (o f the order of  E = E ¤ 1 0 4 ) requi red by the experi m ents using anom al ous scatteri ng. The m i rro rs wi l l b e Rh- coated and op erated at a Ùxed gra zing i ncidence angl e of 3 .5 m ra d gi vi ng a sm ooth reÛection curve in the who l e accessibl e wa velength ra ng e of 0.7{ 1.8 ¡A (7 { 18 keV) tha t covers the K - edges fro m Fe to Y, and the L I I I -edges fro m G d to U. The hi gh p ower of the wi ggl er i s reduced by the rel ati vel y sm al l angul ar acceptance a nd by wi ndo ws and Ùlters resul ti ng i n l ess tha n 200 W rea ching the Ùrst MAD - stati on mi rro r and 160 W on the Ùrst m onochro m ator crysta l . The predi cted chara cteri sti cs of the MAD sta ti on are found in T abl e I II. À
6. E xp er i m ent st at i o n s The experi m ent stati ons wi l l consi st of rel ati vel y sma ll ra di ati on enclosures (a ppro xi m atel y 1 : 2 È 2 : 5 m 2 ) wi th al l equi pm ent i nside bei ng reached f rom the outsi de, i.e. the exp eri menters wi l l no t enter i nto the enclosures. Thi s saves space and also al l ows a m ore rapi d i nterl ock system . The sta ti ons wi l l be equi pp ed wi th hi gh perf orm ance area detecto rs and wi l l al so b e prepa red for a uto m ati on.
R ef er en ces [1] D. Blow , Str uc ture 8 , R77 (2000). [2] Protein Data Bank C urrent H oldings, http: //w w w.rcsb. org/p db/holdin gs.html. [3 ] A .J . Oakley , M. C. Wilce, C li n. E xp. Pharma col. Ph y si ol. 2 7, 145 (2000). [4 ] H .M. Berman, T .N . Bhat, P.E. Bourne, Z. Feng, G. Gilli land, H . W eissig, J . Westbro ok, N at. Stru c t. Bi ol. 957 (2000). [5] R. B. Russell, D. S. Eggleston,
928 (2000).
[6] S. Dry , S. McC arthy , T . H arris,
946 (2000).
[7] R. Bott, R. Bo elens,
391 (1999).
[8] W. Minor, D. R. T omchick, Z. Otw inow ski, [9] A . Brysiak,
Z. Otw inow ski, W. Minor,
R105 (2000).
in: , SY N CR Y S 2001 Bo ok of
A bstracts, p. 63. [10] W. A . H endrickson, C .M. O gata,
494 (1997).
[11] M. A . W alsh, G. Evans, R. Sanishvil i, I . Dementiev a, A . Joachimiak, 1726 (1999).
602
C.B. Mammen et al .
[12] L. M. Rice, T .N . Earnest, A .T . Brunger, Ac ta Cry stall ogr. D 56, 1413 (2000). ¡ . A ndersson, M. Eriksson, L. J . Lindgren, [ 13] A Me thods Ph ys. R es. A 343, 644 (1994).
P. R oj sel, S. W erin, N ucl. I nstru m.
[14] Y . C erenius, K . St¡ahl, L. A . Svensson, T . U rsby , ¡A . Oskarson, J . A lb ertsson, A . Lilj as, J. Syn chrot ron Rad. 7, 203 (2000). [15] MA X -lab, http: //w w w.maxlab. lu. se. [16] E. W all Ç en, G. LeBlanc, M. Eriksson, N uc l. I nstru m. Me thods Ph y s. R es. A 467, 118 (2001). [ 17] K .- J. K im, in: X - ray Data Boo k let, Eds. A .C. T hompson, D. Vaughan, Law rence Berkeley N ational Lab oratory , U niversity of C alif ornia, Berkeley 2001, p. 2- 1. [18] ESRF H ighligh ts 2000, ESRF, Grenoble, 2001, p. 100. [ 19] C. Schulze, U . Lienert, Rad. 5, 77 (1998).
M. H anÛand, M. Lorenzen, F. Zontone, J. Syn chrotr on
[20] A .K . F reund, F. C omin, J .-L. H azemann, R. H ustache, B. J enninger, K . Lieb, M. Pierre, in: Pr oc. SPI E, Vol. 3448, Eds. A .T . Macrander, A .K . Freund, T . Ishik awa, D. M. Mills, 1998, p. 144.
