Solid-State NMR Studies of Structures and Molecular Motions for the Spidroin-Like Polymers

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1 July (Wuli Huaxue Xuebao) Acta Phys -Chim Sin (7) [Article] wwwwhxbpkueducn * ( ) (NMR) (Ala) 5 (PS 2000) (PI 2210) -co- (PS-co- PAL) -co- (PI-co-PAL) C CP/MAS NMR( / ) - (T 1ρ ( C)) (Ala) 5 T 1ρ ( C) : PS-co-PAL PI-co-PAL PI-co-PAL PI CH 2 CH T 1ρ (53±04) ms PS-co- PAL PS CH 2 CH T 1ρ (470±55) ms PI PS (DFT) PS-co-PAL PI-co-PAL (Ala) 5 ( ) β- ; ; ; O641 Solid-State NMR Studies of Structures and Molecular Motions for the Spidroin-Like Polymers DENG Yi-Bin HU Bing-Wen ZHOU Ping * (Key Laboratory of Molecular Engineering of Polymers Ministry of Education Department of Macromolecular Science Fudan University Shanghai P R China) Abstract Using C solid-state nuclear magnetic resonance(nmr) we studied the structures of two spidroin-like polymers which were synthesized by the polymerization of polyalanine ((Ala) 5 ) with oligomers of polystyrene(ps MW=2000) and polyisoprene(pi MW=2210) C CP/MAS (cross polarization/magic angle spinning) NMR spectra and spin-lattice relaxation time in the rotating frame (T 1ρ ( C)) results of the polymers indicated that the chemical shifts of (Ala) 5 in both polymers of polystyrene-co-polyalanine (PS-co-PAL) and polyisoprene-co-polyalanine (PI-co-PAL) were almost the same This means that (Ala) 5 peptide segments in the two polymers have similar chemical environments and secondary structures The similar T 1ρ ( C) values for (Ala) 5 in the two polymers indicate that (Ala) 5 peptide segments also have similar aggregate structures The mechanical properties of the two spidroin-like polymers are quite different: PS-co-PAL is granular and tough while PI-co-PAL is rubber-like and tensible at room temperature This indicates that the mechanical performances of spidroin-like polymers are strongly linked to the properties of the chosen polymers The T 1ρ ( C) values of the skeletons CH 2 CH in PI-co-PAL and PS-co-PAL were (53±04) and (470±55) ms respectively which indicates that PI segments are softer than PS segments in the polymers In addition the density functimal theory (DFT) based chemical shift calculation showed that (Ala) 5 peptide segments in the polymers of PSco-PAL and PI-co-PAL had dihedral angles of ( ) which correspond to a β-sheet conformation Received: February ; Revised: April 2009; Published on Web: May * Corresponding author pingzhou@fudaneducn; Tel: The project was supported by the National Natural Science Foundation of China ( ) ( ) 鬁 Editorial office of Acta Physico-Chimica Sinica

2 1428 Acta Phys -Chim Sin 2009 Vol25 Key Words Polypeptide; Spidroin-like protein polymer; Oligomer; Solid-state NMR GIAO(gauge-independent atomic orbital) [1] [10-] (DFT) C - T 1ρ ( C) [2-4] (Ala) 5 Sogah [4] (polyethylene glycol PEG) (Gly) -co- (PI-co-PAL) (Ala) n (n=4-10) PEG (Ala) n (n=4 6) [3] Yao GlyAlaGlyAla ( ) GlyAlaAlaAlaAla 1 (hexamethylene 11 [214] diisocyanate HDI) [2] [15] (Ala) 5 (PS (Ala) 5 (poly MW=2000) (PI MW=2210) (Ala) 5 PAL) HCl H(Ala) 5 NH(CH 2 ) 6 NH (Ala) 5 H HCl : ( NCO) -co- (PS-co-PAL) C (solid-state NMR) PS-co-PAL PI-co-PAL [5-7] C 40 [8] β- C α C β g L δ α C α C β δ 1 PS PI (Ala) 5 NH(CH 2 ) 6 NH(Ala) CH 2 CH 2 OCONH (CH 2 ) 6 CONH ( Linker) [9] 12 C NMR 1 PS-co-PAL PI-co-PAL Fig1 Chemical formulas of PS-co-PAL and PI-co-PAL

3 No Varian Infinity-Plus mm C 7547 MHz C / (CP/MAS) / (CP/MAS/TOSS) H C 625 khz 1 H 100 khz (adamantine) δ 385 C β 2 PS-co-PAL (A) PS (B) C CP/MAS/ TOSS NMR [1] Fig2 Solid-state C CP/MAS/TOSS NMR spectra of [16] PS-co-PAL (A) and PS (B) The pulse program of CP/MAS/TOSS (cross-polarization/magic-anglespinning/total sideband suppression) was used Contact time pulse C - T 1ρ delay magic-angle-spinning rate and number of acquisition for C NMR measurement of PS-co-PAL are 14 ms 4 s 5 khz and 500 respectively while those for C NMR measurement of PS are 3 ms - 3 s 4 khz and 40 respectively [17] C H 6-311G(dp) - N O 6-31(dp) T 1ρ TMS( ) C T 1ρ : y=aexp(-t/t 1ρ )+y 0 (1) : y=a 1 exp(-t/t I 1ρ )+A 2 exp(-t/t II 1ρ )+y 0 (2) y y 0 T 1ρ PS-co-PAL - A (PS) C CP/MAS/TOSS 2(A T1ρ I T1ρ II [21] I B) 2A δ II - A 1 A (Ala) 5 I II C 襒 O C α C β 1 [18] Talos 1 PS-co-PAL C NMR Table 1 C chemical shift (δ) assignments of PS-co-PAL Peak Domain Group DFT 1717 PAL C 襒 O 1568 Linker C 襒 O 1444 PS C 襒 C 1265 PS C 襒 C C GIAO DFT B3LYP(Becke s three-parameter hybrid method of Lee Yang and Parr) [19] [20] Gaussian PS-co-PAL PI-co- PAL C CP/MAS NMR 477 PAL C α 395 PS CHCH CH 2(CH 2) 4CH 2 (CH 2) PAL C β

1430 Acta Phys -Chim Sin 2009 Vol25 3 PI-co-PAL (A) PI (B) C CP/MAS NMR Fig3 Solid-state C CP/MAS NMR spectra of PI-co-PAL (A) and PI (B) The pulse program of C CP/MAS was used Contact time pulse

4 1430 Acta Phys -Chim Sin 2009 Vol25 3 PI-co-PAL (A) PI (B) C CP/MAS NMR Fig3 Solid-state C CP/MAS NMR spectra of PI-co-PAL (A) and PI (B) The pulse program of C CP/MAS was used Contact time pulse delay magic-angle-spinning rate and number of acquisition for C NMR measurement of PI-co-PAL are 7 ms 2 s 6 khz and 400 respectively while those for C NMR measurement of PI are 2 ms 2 s 5 khz and 2048 respectively PI-co-PAL 4B 85 ms C NMR 4A PI C CP/MAS 3(A B) δ 181 ( I ) δ δ 203 ( II) (Ala) 5 C 襒 O C α 85 ms PI C β δ δ CH 3 δ 186 δ T 1ρ ( C) 2 PI-co-PAL C CP/MAS NMR Table 2 C chemical shift (δ) assignments of PI-co-PAL Peak Domain Group 1712 PAL C 襒 O 1568 Linker C 襒 O 1482 PI C 襒 CH 2 11 PI C 襒 CH PAL C α 418 PI CH 2CH 294 CH 2(CH 2) 4CH 2 (CH 2) a PAL C β 181 PI CH 3 a The peak was observed after spin lock time of 85 ms T 1ρ ( C) 4A T 1ρ ( C) PI-co-PAL C (arrayed-mode) 2D NMR Linker δ 293( 4B) 4B δ A δ 1712 PI-co-PAL C β (Ala) 5 PI CH 3 Linker( ) 3A 4B - C CP/MAS 85 ms 4 PI-co-PAL T 1ρ (t) C arrayed-mode 2D NMR (A) 85 ms C CP/MAS NMR (B) Fig4 Solid-state C arrayed-mode 2D NMR spectrum at different spin lock time (A) and solid-state C CP/MAS NMR spectrum at the spin lock time (t) of 85 ms (B) during T 1ρ measurement for the PI-co-PAL polymer The pulse program of T 1ρx CP was used where T 1ρ is spin-lattice relaxation time in the rotating frame and the subscript x indicates C nucleus here In the arrayed-mode 2D NMR spectrum the dashed line I represents the peak at δ 181 while the lines II III and IV represent the peaks at δ and 1720 respectively Contact time pulse delay magic-angle-spinning rate and number of acquisition are 1 ms 2 s 6 khz and 400 respectively

5 No (Ala) 5 4B 5(A E F) 3A 3 C 襒 O (δ 1710) PI-co-PAL (contact time) 1 ms 5 PS-co-PAL PI-co- PAL T 1ρ ( C) PI CH 2 CH 5A(δ 1717) 5E(δ 1712) 5F (δ 481) 5B(δ 477) 5C(δ 405) PS-co-PAL 1 H C 襒 O C C PIco-PAL C α (δ 481) (δ 418) PI-co-PAL C β (δ 201) PI CH 3 (δ 181) 5D(δ 207) 5G(δ 418) 5H(δ 181) T 1ρ 3 PS-co-PAL PS CH 2 CH (δ 405) T 1ρ (470±55) ms PI- R co-pal PI CH 2 CH (δ 418) T 1ρ 5(B C D G H) (53±04) ms PS PI PS-co-PAL PI-co-PAL 5 Fig5 PS-co-PAL(A B C D) PI-co-PAL(E F G H) T 1ρ ( C) Exponential decays and simulations of PS-co-PAL(A B C D) and PI-co-PAL(E F G H) during T 1ρ ( C) measurements Black dots represent the experimental data and solid lines represent simulated curves B C D G and H were simulated with single exponential function based on the Eq(1) while A E and F were simulated with double exponential function based on the Eq(2)

1432 Acta Phys -Chim Sin 2009 Vol25 3 PS-co-PAL PI-co-PAL T 1ρ ( C) Table 3 Simulation results of T 1ρ ( C) measurements for PS-co-PAL and PI-co-PAL polymers Polymer δ Domain 10 3 A T 1ρ /ms Group

6 1432 Acta Phys -Chim Sin 2009 Vol25 3 PS-co-PAL PI-co-PAL T 1ρ ( C) Table 3 Simulation results of T 1ρ ( C) measurements for PS-co-PAL and PI-co-PAL polymers Polymer δ Domain 10 3 A T 1ρ /ms Group PS-co-PAL 1717 Ala ±08 486±585 C 襒 O Linker 08±09 86±3 C 襒 O 477 Ala 52±02 531±56 C α 405 PS 148±07 470±55 CH 2CH 207 Ala 32±03 626±154 C β PI-co-PAL 1712 Ala 34± ±500 C 襒 O Linker ± 10±09 C 襒 O 481 Ala 31±03 694±225 C α PI 41±03 29±05 CH 2CH 418 PI 2±05 53±04 CH 2CH 181 PI 0±02 102±02 CH 3 PS PI (Ala) 5 PS-co-PAL Ala C α (δ 477) T 1ρ (531±56) ms 23 PS-co-PAL PI-co-PAL PI-co-PAL T 1ρ (694±225) ms Ala PS-co-PAL PS-co-PAL PI-co-PAL PI-co-PAL ; PS-co-PAL NMR δ C 襒 O (δ 1717) T 1ρ 20 Talos (486±585) (86±3) ms Ala ((-2±5) (142±5) ) - Ala (Ala) 5 DFT Linker CH 2 CONH ( δ calc -δ expt 05) 4 PI-co-PAL C 襒 O (δ 1712) T 1ρ (Ala) 5 Ala ( ) (1215±500) (10±09) ms (Ala) 5 β- Linker ; (Ala) 5 β- PS-co-PAL PI-co-PAL nm T 1ρ PS nm 0342 nm PI (Ala) 5 β- PS-co-PAL PI-co-PAL [22] NMR 4 PS-co-PAL PI-co-PAL (Ala) 5 ( ) (Ala) 5 Talos 0323 Table 4 Experimental and theoretical chemical nm shifts and Talos-predicted and theoretical dihedral angles of (Ala) 5 segments in the polymers of PS-co-PAL and PI-co-PAL δ expt δ calc Dihedral angle ( ) Group PS-co-PAL PI-co-PAL (Ala) 5 Talos-predicted DFT-based C α C β (-2±5) (142±5) C 襒 O ( ) PS-co-PAL PI-co-PAL (Ala) 5 Fig6 Structural model of aggregate of (Ala) 5 in the spidroin-like polymer PS-co-PAL or PI-co-PAL constructed based on the dihedral angles of ( ) The dashed lines represent the hydrogen bonds between H and O atoms β- β- 3

7 No PS-co-PAL PI-co-PAL [ - PS-co-PAL PIco-PAL (Ala) 5 β- ( ) C α T 1ρ ms PS PI 112: 8251 PS-co-PAL PI-co-PAL J Comput Chem : 230 PS PS-co-PAL CH 2 CH T 1ρ ( C)=(470±55) ms; PI PI-co-PAL CH 2 CH T 1ρ ( C)=(53±04) ms 5 Deng Y B; Ji D; Zhou P Chin J Magn Reson : : 555] 6 Yao J M; Nakazawa Y; Asakura T Biomacromolecules : Xie X; Zhou P; Deng F; Wu P Y; Zong X H; Yao W H Chem J Chin Univ : 961 [ : 961] 8 Saito H Magn Reson Chem : Spera S; Bax A J Am Chem Soc : Wolinski K; Hinton J F; Pulay P J Am Chem Soc Weiner S J; Kollman P A; Nguyen D T; Case D A 12 de Dios A C; Pearson J G; Oldfield E Science : 1491 de Dios A C; Pearson J G; Oldfield E J Am Chem Soc : Zhou C C Ph D Dissertation Shanghai: Fudan University 2004 [ : 2004] 15 Gross E; Meienhofer J The peptides: analysis synthesis biology San Diego: Academic Press : Gabrielse W; Gaur H A; Feyen F C; Veeman W S Macromolecules : Nielsen N C; Bildsoe H; Jakobsen H J Macromolecules Cornilescu G; Delaglio F; Bax A J Biomol NMR 1999 : 289! Becke A D J Chem Phys : 5648 Frisch M J; Trucks G W; Schlegel H B; et al Gaussian 98 revision A1 Wallingford USA: Gaussian Inc 1998 References 21 Zhou P; Li G Y; Shao Z Z; Pan X Y; Yu T Y J Phys 1 Lewis R V Chem Rev : 3762 Chem B : Zhou C C; Leng B X; Yao J R; Qian J; Chen X; Zhou P; Knight D P; Shao Z Z Biomacromolecules : Cappello J; McGrath K P Spinning of protein polymer fibers In: Kaplan D L; Adams W W; Farmer B; Viney C Ed 3 Yao J R; Xiao D H; Chen X; Zhou P; Yu T Y; Shao Z Z Macromolecules : 7508 Silk polymers: materials science and biotechnology Washington DC: American Chemical Society Symposium Series : 4 Rathore O; Sogah D Y J Am Chem Soc :

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