Crystal Structure of - American Chemical Society

23 Crystal Structure of (1->3)-α-D-Glucan K O Z O O G A W A — R a d i a t i o n Center of Osaka Prefecture, Sakai, Osaka 593 Japan

Downloaded by UNIV OF MICHIGAN ANN ARBOR on February 18, 2015 | http://pubs.acs.org Publication Date: November 17, 1980 | doi: 10.1021/bk-1980-0141.ch023

K E I Z O O K A M U R A — D e p a r t m e n t of Wood Science and Technology, Faculty of Agriculture, Kyoto University, Kyoto 606 Japan S A C H I K O OKA and A K I R A MISAKI—Department of Food and Nutrition, Faculty of Science and Living, Osaka City University, Osaka 558 Japan

B o t h i n t h e o r y and i n p r a c t i c e t h e r e e x i s t e i g h t g l u c o p y r a n o s e h o m o p o l y m e r s , and some o f t h e m o l e c u l a r c o n f o r m a t i o n s o f t h r e e o f t h e s e , i . e . c e l l u l o s e and a m y l o s e Q.,2.,_3,4_) , and ( 1 + 3 ) β-D-glucan C5,j6,7) h a v e b e e n e s t a b l i s h e d b y x - r a y a n a l y s i s . A l t h o u g h ( l + 3 ) - a - D - g l u c a n i s among t h e f i v e homopolymers p r e v i o u s l y u n s o l v e d by x-ray d i f f r a c t i o n , p o s s i b l e c h a i n c o n f o r m a t i o n s w e r e p r e d i c t e d w i t h c o m p u t e r s t o b e an e x t e n d e d r i b b o n (JL»£) 9 s i n g l e h e l i x (9) , o r a d o u b l e o r t r i p l e h e l i x (10) . (l+3)-a-D-Glucan i s m a i n l y found i n micro-organisms o r i n t h e c e l l w a l l s o f many k i n d s o f f u n g i and y e a s t ( 1 1 , 1 2 , 1 3 ) . X - r a y powder p a t t e r n s o f t h e f u n g a l g l u c a n s h a v e b e e n e x t e n s i v e l y s t u d i e d b y J e l s m a and K r e g e r ( 1 4 , 1 5 ) . They r e p o r t e d t h a t t h e g l u c a n c r y s t a l l i z e d as t h r e e p o l y m o r p h s ( I - m ) ; p o l y m o r p h I was o b s e r v e d o n l y i n n a t i v e t i s s u e , I I ( h y d r a t e form) a p p e a r e d on p r e c i p i t a t i o n o f t h e g l u c a n f r o m a l k a l i n e s o l u t i o n , and ΠΙ ( d e h y d r a t e d form) a r o s e a f t e r d r y i n g . B a c t e r i a f o u n d i n human s a l i v a a l s o produce (l+3)-a-D-glucans t h a t a r e i n t e r e s t i n g i n connection w i t h dental caries (16). S p e c i f i c a l l y , Streptococcus mutans a n d S t r e p t o c o c c u s s a l i v a r i u s s y n t h e s i z e f r o m s u c r o s e α-glucans t h a t a r e v e r y s t i c k y and i n s o l u b l e i n w a t e r . The glucans have a (l+3)-a-D-glucan backbone w i t h s h o r t s i d e c h a i n s o f ( 1 + 6 ) - a - ( a n d a l s o ( 1 + 4 ) - a - f o r JS. s a l i v a r i u s ) l i n k e d g l u c o s e residues. These g l u c a n s f o r m d e n t a l p l a q u e s and c o n s e q u e n t l y contribute to dental caries. The p u r p o s e o f o u r s t u d y was t o o b t a i n a w e l l - d e f i n e d x - r a y f i b e r p a t t e r n o f a b a c t e r i a l ( l + 3 ) - a - D - g l u c a n , a n d , b a s e d on t h e p a t t e r n , t o d e t e r m i n e t h e c o n f o r m a t i o n o f t h e g l u c a n . We b e l i e v e t h a t knowledge o f m o l e c u l a r c o n f o r m a t i o n i s i m p o r t a n t f o r u n d e r s t a n d i n g p l a n t p h y s i o l o g y and t h e d e n t a l s i g n i f i c a n c e o f (1+3)-ot-D-glucan. I t would a l s o p r o v i d e b a s i c knowledge u s e f u l i n t h e s t u d y o f more c o m p l i c a t e d h e t e r o p o l y s a c c h a r i d e s c o n t a i n i n g ( 1 + 3 ) - l i n k e d α-D-glucopyranose u n i t s . X - r a y powder p a t t e r n s o f our b a c t e r i a l samples a r e a l s o r e p o r t e d f o r comparison w i t h those o f f u n g a l (1+3)-α-D-glucans r e p o r t e d b y J e l s m a and K r e g e r ( 1 4 ) . a

0-8412-05 89-2/ 80/47-141 -35 3$05.00/0 © 1980 American Chemical Society In Fiber Diffraction Methods; French, A., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

354

F I B E R

D I F F R A C T I O N

M E T H O D S


Experimental Sample o f s a l i v a r i u s . As p r e v i o u s l y reported (17), a l i n e a r g l u c a n c o n s i s t i n g s o l e l y o f ( l - * 3 ) - a - D - g l u c o s i d i c l i n k a g e s was p r e p a r e d b y m i l d S m i t h d e g r a d a t i o n o f a n a - g l u c a n p r o d u c e d b y S^. s a l i v a r i u s T T L - L P 1 . V i s c o s i t y measurement o f t h e g l u c a n gave [n] = 0.52 d l / g i n 0.5N NaOH s o l u t i o n a t 25°C ( s a m p l e A, powder form). Since attempts t o prepare a continuous f i l m o r f i b e r from s o l u t i o n s o f s a m p l e A i n aqueous a l k a l i , h y d r a z i n e h y d r a t e , o r N - m e t h y l m o r p h o l i n e N-oxide-DMSO m i x t u r e w e r e n o t s u c c e s s f u l , t h e g l u c a n was a c e t y l a t e d a n d a c o n t i n u o u s t r a n s p a r e n t f i l m o f t h e g l u c a n a c e t a t e was o b t a i n e d f r o m a 5% s o l u t i o n i n c h l o r o f o r m . A w e l l - o r i e n t e d g l u c a n f i l m was o b t a i n e d b y s t r e t c h i n g t h e g l u c a n a c e t a t e f i l m b y 6.5 t i m e s i t s o r i g i n a l l e n g t h i n g l y c e r i n e a t 150°C a n d d e a c e t y l a t i n g i n 2M s o d i u m m e t h y l a t e - m e t h y l a l c o h o l solution. The l o w c r y s t a l l i n i t y o f t h i s f i l m was s u b s t a n t i a l l y i m p r o v e d b y a n n e a l i n g i n w a t e r a t 140°C, u n d e r t e n s i o n , i n a s e a l e d bomb ( s a m p l e B, o r i e n t e d f i l m ) . A n o t h e r o r i e n t e d f i l m made f r o m s a m p l e A was p r e p a r e d b y t h e same p r o c e d u r e a s f o r s a m p l e B, e x c e p t t h a t s a m p l e A was pretreated w i t h hydrazine hydrate. The v i s c o s i t y was [ n ] = 0.50 d l / g i n 0.5N NaOH ( s a m p l e C, o r i e n t e d f i l m ) . Sample o f m u t a n s . A (l-*-3)-a-D-glucan s u p p l i e d by D r . Sudo was p r e p a r e d b y d e x t r a n a s e d e g r a d a t i o n o f a n a - g l u c a n p r o d u c e d b y !S. mutans OMZ 176 i n a s u c r o s e medium ( 1 6 ) . The number a v e r a g e degree o f p o l y m e r i z a t i o n o f t h e g l u c a n , determined by t h e m o d i f i e d S o m o g y i - N e l s o n method (18) w i t h l a m i n a r i b i o s e a s a s t a n d a r d , was 43.8. The DP o f s a m p l e A c o u l d n o t b e d e t e r m i n e d by t h i s method i n d i c a t i n g t h a t t h e g l u c a n p r o d u c e d b y j>. s a l i v a r i u s glucan had a h i g h e r molecular weight. Mutan was s o l u b l e i n DMSO b u t d i d n o t p r o d u c e a n y c o n t i n u o u s f i l m f r o m DMSO s o l u t i o n o r a n y o t h e r s o l v e n t m e n t i o n e d a b o v e . Sample D was t h e r e f o r e mutan powder. I t s v i s c o s i t y was [r|] = 0.33 d l / g i n 0.5N NaOH. M e t h o d s . The w i d e a n d s m a l l a n g l e x - r a y p a t t e r n s w e r e r e c o r d e d i n a f l a t f i l m camera a t c o n t r o l l e d r e l a t i v e h u m i d i t y u s i n g N i - f i l t e r e d CuKa r a d i a t i o n g e n e r a t e d a t 40 kV a n d 15 mA. The d e n s i t y o f t h e g l u c a n f i l m s w e r e measured b y f l o t a t i o n i n a carbon t e t r a c h l o r i d e - m - x y l e n e mixture. Results F i b e r p a t t e r n s . I n vacuum, t h e s t r e t c h e d a n d a n n e a l e d g l u c a n f i l m made f r o m _S. s a l i v a r i u s ( s a m p l e B) gave a c l e a r x - r a y p a t t e r n a s shown i n F i g u r e 1 ( 1 7 ) . A l l 29 r e f l e c t i o n s ( F i g u r e 2) can be i n d e x e d w i t h an orthorhombic u n i t c e l l ( T a b l e s I and I I ) . I n t h e p r e v i o u s r e p o r t ( 1 7 ) , t h e u n i t c e l l was r e p o r t e d t o b e

In Fiber Diffraction Methods; French, A., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.


OGAWA

ET

AL.

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Figure 1. X-rayfiberdiagram of Sample B in vacuum. Thefiberaxis is vertical

an


356

FIBER

DIFFRACTION

METHODS


TABLE I OBSERVED SPACINGS AND INTENSITIES FOR THE F I B E R PATTERN I N VACUUM h k 1

Spacing(nm) calc. obs.

2 1 2 0 3 1 2 4 4 1 4 5 3 6

0 1 1 2 1 2 2 0 1 3 2 1 3 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0

0.823 ^ 0.821 0.826 0.623 0.628 0.477' 0.476 V 0.476 0.459 J 0.4131 | 0.410 0.412 0.378 0.373 0.313'1 0.312 • 0.311 0.311, 0.275 ^ 0.275 0.274

0 1 1 2 2 0 3 1 2 4 4 3 5 0 6

0 0 1 0 1 2 1 2 2 0 1 2 0 3 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0.844 0.844 0.751 0.758 0.5901 [• 0.587 0.589, 0.501 0.503 0.416' 0.414 - 0.414 0.403 0.371' 0.371 0.370, 0.345' f 0.338 0.331 0.3071 } 0.299 0.298 0.252 0.253

Int.* (obs.)

1

o o

S vs M W W

1

1

VW VW VW W s vs M

h k 1

S p a c i n g (nm) calc. obs.

0 1 2 2 0 3 2 4 3 0 1 4 5

0 1 0 1 2 1 2 0 2 3 3 2 1

2 2 2 2 2 2 2 2 2 2 2 2 2

0.422 0.422 0.376] 0.377 0.375 J 0.349 0.348 0.3161 0.314 0.316 0.295\ 0.295 0.295j 0.274 0.275 0.254' 0.251 • 0.254 0.251 0.251 ,

1 0 1 2 2 3 0 3

0 1 1 0 1 0 2 1

3 3 3 3 3 3 3 3

0.2771 0.276 0.270, 0.2661 0.265 0.266 , 0.256 0.255 0.250] 0.242 '0.242 0.242 ,

0 0 4 2 1 4

Int.* (obs.) s VW s

r J

0.211 0.200

0.210 0.200

M VW W W

s W VW w

VW w

W W W

*VS, v e r y s t r o n g ; S, s t r o n g ; M, medium; W, weak; VW, weak

very


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ET AL.

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357

TABLE I I CRYSTAL DATA FOR THE F I B E R PATTERN I N VACUUM C r y s t a l system Space group

Orthorhombic

a (nm)* _b (nm)* c_(fiber a x i s ) ( n m ) * Volume ( n m ) Number o f glucose residue p(calc.)(g/cm ) p(obs. )(g/cm ) Number o f c h a i n

1.646±0.005 0.955±0.003 0.844±0.001 1.327


3

3

3

H e l i x parameters n h (nm)

8 1.62 1.54 4 2 0.422

* L a t t i c e parameters were o b t a i n e d by a l e a s t - s q u a r e s r e f i n e m e n t program.

m o n o c l i n i c w i t h a = 0.823 nm, b = 0.955 nm, c_ ( f i b e r a x i s ) = 0.844 nm, and y = 90°. However, b y i n c r e a s i n g t h e e x p o s u r e t i m e , a v e r y weak new r e f l e c t i o n a p p e a r e d a t 0.758 nm o n t h e f i r s t layer line. The a. a x i s was d o u b l e d i n o r d e r t o a c c o m o d a t e t h e new r e f l e c t i o n w h i c h i n d e x e d a s t h e ( 1 0 1 ) r e f l e c t i o n ( T a b l e I ) . P 2 ^ 2 ^ 2 ^ seems t o b e t h e b e s t s p a c e g r o u p ( T a b l e I I ) . As t h e r e l a t i v e h u m i d i t y was i n c r e a s e d ( 7 6 % a n d 9 8 % ) , t h e g l u c a n f i l m ( s a m p l e B) showed a n a d d i t i o n a l r e f l e c t i o n on t h e e q u a t o r h a v i n g medium i n t e n s i t y a n d a d_ v a l u e o f 0.971 nm, c o r r e s p o n d i n g t o t h e (010) r e f l e c t i o n ( T a b l e I ) . The a p p e a r a n c e and d i s a p p e a r a n c e o f t h e ( 0 1 0 ) r e f l e c t i o n i s r e v e r s i b l e w i t h changing r e l a t i v e humidity. Sample C, w h i c h was p r e p a r e d b y p r e t r e a t i n g s a m p l e A w i t h h y d r a z i n e h y d r a t e , gave a f i b e r p a t t e r n w i t h s p a c i n g s i d e n t i c a l t o t h a t o f s a m p l e B. The r e f l e c t i o n s p o t s o f s a m p l e C a r e somewhat s h a r p e r a n d more a r c k e d t h a n t h o s e o f s a m p l e B, i n d i c a t i n g h i g h e r c r y s t a l l i n i t y a n d l e s s orientation. However, t h e f i b e r p a t t e r n o f s a m p l e C d i d n o t show the (010) r e f l e c t i o n a t h i g h e r h u m i d i t y . The x - r a y f i b e r p a t t e r n o f s a m p l e B b e f o r e a n n e a l i n g d i d n o t d i f f e r e s s e n t i a l l y from t h a t o f t h e annealed f i l m , though t h e c r y s t a l l i n i t y was c o n s i d e r a b l y l o w e r . S m a l l a n g l e x - r a y s c a t t e r i n g o f t h e o r i e n t e d f i l m s (samples B a n d C) showed a d i s c r e t e i n t e r f e r e n c e a l o n g t h e f i b e r a x i s c o r r e s p o n d i n g t o a l o n g p e r i o d o f 14.0 nm ( F i g u r e 3 ) . The s t r e t c h e d f i l m o f s a m p l e D p r e p a r e d w i t h t h e same r e g e n e r a t i o n p r o c e d u r e u s e d f o r s a m p l e B showed no o r i e n t a t i o n . T h i s would be


FIBER DIFFRACTION

358

L2p4

214

303 023 313 \


113 203 103 013

032 132 422 512 \

213

111 212

002 112 202

001^

N

^ \ 022 312

322

501 221 0^1 211 \ \ 021 111 321 130 201 420 121 220 510 210 400

•A

200

Figure 2. Indexed schematic display of the x-ray pattern corresponding to that in Figure 1

METHODS

no

1

I

020 310 120

I

I

410

EQUATOR

Figure 3. The small-angle x-ray scattering of Sample B in vacuum


\ 611

330 600

23.

OGAWA

ET AL.

due

t o i t s lower molecular

Crystal Structure of (l-3)-o:-D'Glucan

359

weight.


Powder p a t t e r n s . Sample A was h i g h l y c r y s t a l l i n e a n d showed two i n t e r c o n v e r t i b l e powder p a t t e r n s : one a t h i g h r e l a t i v e h u m i d i t y ( 7 6 % - 9 8 % ) , a n d t h e o t h e r i n v a c u o ( T a b l e H I ) . The d spacings o f these p a t t e r n s d i f f e r from those o f f i b e r p a t t e r n s o f e i t h e r s a m p l e B o r s a m p l e C ( T a b l e I ) . M u t a n ( s a m p l e D) a l s o showed a c l e a r p a t t e r n s i m i l a r t o t h a t o f s a m p l e A i n v a c u o . However, t h i s p a t t e r n d i d n o t change b y v a r y i n g t h e r e l a t i v e h u m i d i t y ( T a b l e HE).

TABLE I E OBSERVED SPACINGS AND INTENSITIES FOR POWDER PATTERNS . salivarius (sample A) a t 76% and 98% r . h . 0.966 (VS) 0.788 (VW) 0.639 (VW) 0.542 (VW) 0.498 (VS) 0.423 0.395 0.362 0.323 0.304 0.273 0.261 0.212 0.202

(VS) (W) (W) (M) (VW) (M) (VW) (W) (VW)

J5. mutans ( s a m p l e D)

i n vacuum

at a l l r . h . studied

0.870

(S)

0.868

(S)

0.627

(S)

0.624

(S)

0.518 (M) 0.459 (VS) 0.415 (VS)

0.514 (M) 0.457 (VS) 0.412 (VS)

(W) 0.383 0.348 (VW) (W) 0.315 0.281 (W)

0.382 (W) 0.351 (VW) 0.316 (W) 0.278 (W)

0.259 (W) 0.215 (VW) 0.204 (VW)

0.256 (W) 0.216 (VW) 0.198 (VW)

Discussion F i b e r p a t t e r n s . D e s p i t e t h e p r e s e n c e o f a (001) r e f l e c t i o n ( F i g u r e 1 ) , a t w o f o l d screw a x i s a l o n g t h e f i b e r a x i s has been i n c o r p o r a t e d i n t o t h e (l->3)-a-D-glucan backbone c o n f o r m a t i o n , because t i l t i n g t h e o r i e n t e d f i l m causes t h e (002) and (004) r e f l e c t i o n s t o become s t r o n g , b u t n o t t h e ( 0 0 1 ) . Therefore,the p r e s e n c e o f a v e r y weak ( 0 0 1 ) r e f l e c t i o n i s l i k e l y d u e t o a s l i g h t d i s o r d e r o f 0 ( 6 ) a l o n g t h e g l u c a n c h a i n . The v a l u e o f h , t h e a d v a n c e p e r r e s i d u e a l o n g t h e h e l i x a x i s , 0.422 nm ( T a b l e I I ) , i s v e r y c l o s e t o t h e v i r t u a l bond l e n g t h o f 0.428 nm



360

FIBER DIFFRACTION

METHODS

determined f o r a-D-glucose (19). This i n d i c a t e s t h a t the (l-K3)-a-D-glucan m o l e c u l e i s almost e n t i r e l y extended a l o n g t h e f i b e r a x i s as p r e d i c t e d by t h e c o n f o r m a t i o n a l c a l c u l a t i o n s (8,j)). C o n f o r m a t i o n and p a c k i n g r e f i n e m e n t o f t h e ( l - * 3 ) - a - D - g l u c a n m o l e c u l e a r e underway i n c o l l a b o r a t i o n w i t h P r o f e s s o r A n a t o l e S a r k o , and t h e s e r e s u l t s w i l l be a v a i l a b l e s o o n . P r e l i m i n a r y i n d i c a t i o n s a r e t h a t t h e a d j a c e n t c h a i n s have o p p o s i t e s e n c e a l o n g t h e b a x i s and t h e m o l e c u l e s a r e e x t e n s i v e l y h y d r o g e n b o n d e d . As w i t h c e l l u l o s e , t h i s u n d o u b t e d l y a c c o u n t s f o r t h e i n s o l u b i l i t y of t h i s glucan. The d i s c r e t e i n t e r f e r e n c e i n s m a l l a n g l e x - r a y s c a t t e r i n g ( F i g u r e 3) c o r r e s p o n d s t o a p e r i o d o f 14 nm. T h i s s p a c i n g may be a t t r i b u t a b l e t o chain f o l d i n g of the glucan molecule along the fiber axis. T h i s i n t e r p r e t a t i o n i s i n k e e p i n g w i t h an a n t i p a r a l l e l p a c k i n g o f t h e g l u c a n c h a i n , as r e q u i r e d by t h e symmetry o f t h e P2^2^2- s p a c e g r o u p . T h i s t y p e o f d i s c r e t e d i f f r a c t i o n i s also noticeable i n F o r t i s a n f i b e r (20). I n that c a s e , c e l l u l o s e a c e t a t e f i b e r was s a p o n i f i e d t o r e g e n e r a t e d c e l l u l o s e , then t r e a t e d w i t h d i l u t e h y d r o c h l o r i c a c i d . The l o n g s p a c i n g o f (l-K3)-a-D-glucan i s t h e r e f o r e another s i m i l a r i t y t o a m i c r o s t r u c t u r a l feature of c e l l u l o s e . Sample B, w h i c h i s l e s s c r y s t a l l i n e t h a n s a m p l e C, showed an a d d i t i o n a l s p o t on t h e e q u a t o r c o r r e s p o n d i n g t o a ( 0 1 0 ) r e f l e c t i o n a t h i g h r e l a t i v e h u m i d i t y . We s u g g e s t t h a t t h i s s p o t i s due t o a s l i g h t d i s o r d e r o f t h e m o l e c u l e a l o n g t h e b a x i s . T h i s d i s o r d e r w o u l d be c a u s e d by t h e a d d i t i o n o f a w a t e r m o l e c u l e t o t h e g l u c a n c h a i n . T h e r e f o r e , t h e P 2 ^ 2 ^ 2 symmetry i s l o s t . 1

Powder p a t t e r n s . A l l t h e powder p a t t e r n s o f o u r b a c t e r i a l g l u c a n s were s i m i l a r t o those o f f u n g a l (l-*3)-ot-D-glucans ( 1 4 ) . The c r y s t a l s t r u c t u r e o f s a m p l e A ( g l u c a n f r o m S_. s a l i v a r i u s ) a t h i g h r e l a t i v e humidity corresponded t o Kreger's polymorph I I ( h y d r a t e d f o r m ) , and t h e powder p a t t e r n s o f s a m p l e A i n v a c u o a s w e l l a s s a m p l e D (mutan) a t a l l h u m i d i t i e s c o r r e s p o n d e d t o h i s p o l y m o r p h HE ( d e h y d r a t e d f o r m ) . I t i s n o t e w o r t h y t h a t t h e c r y s t a l s t r u c t u r e o f low m o l e c u l a r weight (l-K3)-a-D-glucan ( s a m p l e D) i s n o t a f f e c t e d b y t h e p r e s e n c e o f w a t e r . Similar f i n d i n g s have been r e p o r t e d i n t h e case o f (l-K3)-B-D-glucan (paramylon o r c u r d l a n ) ( 2 1 ) . D u r i n g o u r s t u d y , J e l s m a and K r e g e r o b t a i n e d t h r e e f i b e r p a t t e r n s from a " n a t i v e " trama t i s s u e o f P i p t o p o r u s b e t u l i n u s , which they c l a s s i f i e d as polymorphs I-Itt o f (l-K3)-a-D-glucan. T h e i r f i b e r p a t t e r n s a r e l e s s o r i e n t e d than our p a t t e r n s from r e g e n e r a t e d g l u c a n , and t h e f u n g a l ( 1 + 3 ) - a - D - g l u c a n s a r e c o n t a m i n a t e d b y (l->3)-B-D-glucan ( 1 5 ) . S i n c e o u r f i b e r p a t t e r n s are from "regenerated" m a t e r i a l , our c r y s t a l s t r u c t u r e i s d i f f e r e n t f r o m any o f K r e g e r ' s p o l y m o r p h s and i t m i g h t be named polymorph IV i n e x t e n s i o n o f Kreger's c l a s s i f i c a t i o n . I n t e r e s t i n g l y , a l l o f t h e i r p a t t e r n s h a v e i d e n t i c a l n (number o f g l u c o s e r e s i d u e s p e r one t u r n o f t h e h e l i x ) and s i m i l a r h v a l u e s ,



23.

OGAWA E T AL.

Crystal Structure of (l-3)-a-D-Glucan

361

c l o s e t o o u r v a l u e s ( T a b l e I I ) . However, t h e s e f o u r p o l y m o r p h s have d i f f e r e n t c r y s t a l parameters f o r dimensions o t h e r than t h e fiber axis. These r e s u l t s suggest t h a t t h e t y p i c a l c h a i n c o n f o r m a t i o n o f ( l + 3 ) - a - D - g l u c a n i s a 2^ r i b b o n , m a x i m a l l y extended a l o n g t h e f i b e r a x i s . This i s another s i m i l a r i t y t o c e l l u l o s e f o r w h i c h f o u r polymorphs ( c e l l u l o s e I - I V ) have t h e same f i b e r p e r i o d , 1.03 nm. The c h a n g e o f t h e c r y s t a l s t r u c t u r e o f ( 1 + 3 ) - a - D - g l u e a n s h o u l d b e compared t o t h e c a s e o f ( l + 3 ) - $ - D - g l u c a n ( c u r d l a n ) . A l t h o u g h c u r d l a n changes i t s p o l y m o r p h i c form by a n n e a l i n g ( 6 ) , n e i t h e r t h e f i b e r p a t t e r n s ( s a m p l e s B a n d C) n o r t h e powder p a t t e r n s ( s a m p l e s A a n d D) u n d e r w e n t p o l y m o r p h i c t r a n s f o r m a t i o n s due t o a n n e a l i n g . K r e g e r a n d J e l s m a s u g g e s t e d t h a t p o l y m o r p h I I was e n e r g e t i c a l l y more s t a b l e t h a n p o l y m o r p h HI ( 1 4 ) . However, we do n o t a g r e e , s i n c e s a m p l e D (mutan) showed t h e powder p a t t e r n o f p o l y m o r p h HI a t a l l r e l a t i v e h u m i d i t i e s , we b e l i e v e t h e d e h y d r a t e d f o r m i s more s t a b l e t h a n t h e h y d r a t e d f o r m . F u r t h e r m o r e , p o l y m o r p h I V ( r e g e n e r a t e d f o r m ) seems t o b e e v e n more s t a b l e . I t s f i b e r p a t t e r n d i d n o t change s i g n i f i c a n t l y w i t h varying r e l a t i v e humidity. Acknowledgements We t h a n k D r . R. H. M a r c h e s s a u l t o f X e r o x R e s e a r c h C e n t r e o f Canada a n d P r o f e s s o r A. S a r k o o f S t a t e U n i v e r s i t y o f New Y o r k , C o l l e g e o f E n v i r o n m e n t a l S c i e n c e and F o r e s t r y f o r t h e i r u s e f u l s u g g e s t i o n s on a n a l y z i n g x - r a y f i b e r p a t t e r n s . The s a m p l e o f S t r e p t o c o c c u s mutans was k i n d l y g i v e n b y D r . M. Sudo o f K a n o n j i I n s t i t u t e , R e s e a r c h F o u n d a t i o n f o r M i c r o b i a l D i s e a s e s , Osaka U n i v e r s i t y , t o whom we a r e i n d e b t e d .

Abstract A linear (1->3)-α-D-glucan (sample A) was prepared by mild Smith degradation from a b a c t e r i a l α-glucan elaborated by a s t r a i n of S. s a l i v a r i u s TTL-LP1. The oriented glucan film (sample B) was obtained by acetylating the glucan, followed by stretching i n glycerine at 150°C and deacetylation. Annealing the oriented film i n water at 140°C, under tension i n a sealed bomb, improved the crystallinity. All the 29 reflections on the equator and four layer lines were indexed with an orthorhombic unit cell with a = 1.646 nm, b = 0.955 nm, and c (fiber axis) = 0.844 nm. P212121 seemed to be the best space group. The c r y s t a l structure of sample A and another bacterial (1->3)-α-D -glucan (sample D) prepared from S. mutans fell i n two of three polymorphs I-III of fungal (1->3)-α-D-glucan reported by Jelsma and Kreger; the c r y s t a l structure of sample B might be named as polymorph IV. All polymorphs of (l->3)-α-D-glucan observed to date have almost i d e n t i c a l h e l i x parameters n = 2 and h = 0.422


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nm. These h values are close to the v i r t u a l bond length of 0.428 nm determined for α-D-glucose, suggesting that the t y p i c a l chain conformation i s an extended, ribbon-like structure. The s i m i l a r i t i e s of (1->3)-α-D-glucan to cellulose are discussed. Literature Cited 1. Downloaded by UNIV OF MICHIGAN ANN ARBOR on February 18, 2015 | http://pubs.acs.org Publication Date: November 17, 1980 | doi: 10.1021/bk-1980-0141.ch023

2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.

Marchessault, R. H . ; Sarko, A. Advan. Carbohydr. Chem., 1967, 22, 421-482. Marchessault, R. H . ; Sundararajan, P. R. Advan. Carbohydr. Chem. Biochem., 1976, 33, 387-404. Sundararajan, P. R.; Marchessault, R. H. Advan. Carbohydr. Chem. Biochem., 1978, 35, 377-385. French, A. D. Bakers Digest, 1979, 53, 39-46,54. Jelsma, J.; Kreger, D. R. Carbohydr. Res.,1975, 43, 200-203. Marchessault, R. H . ; Deslandes, Y . ; Ogawa, K.;Sundararajan, P. R. Can. J. Chem., 1977, 55, 300-303. Bluhm, T. L.; Sarko, A. Can. J. Chem., 1977, 55, 293-299. Rees, D. A . ; Scott, W. E. J . Chem. Soc., 1971, B, 469-479. Sathyanarayana, B. K . ; Rao, V. S. R. Biopolymers, 1972, 11, 1379-1394. Bluhm, T. L.; Sarko, A. Carbohydr. Res., 1977, 54, 125-138. Kreger, D. R. Biochim. Biophys. Acta, 1954, 13, 1-10. Johnston, I . R. Biochem. J., 1965, 96, 659-664. Bacon, J. S. D . ; Jones, D . ; Farmer, V. C.; Webley, D. M. Biochim. Biophys. Acta, 1968, 158, 313-315. Jelsma, J.; Kreger, D. R. Carbohydr. Res., 1979, 71, 51-64. Jelsma, J. Doctoral dissertation, 1979, University of Groningen. Ebisu, S.; Misaki, A . ; Kato, K . ; Kotani, S. Carbohydr. Res., 1974, 38, 374-381. Ogawa, K . ; Misaki, A . ; Oka, S.; Okamura, K, Carbohydr. Res., 1979, 75, C13-C16. Hiromi, K . ; Takasaki, Y.; Ono, S. B u l l . Chem. Soc. Jpn., 1963, 36, 563-569. Brown, G. M . ; Levy, H. A. Science, 1965, 147, 1038-1039. Schulz, J.; John, K. Cellulose Chem. Technol., 1975, 9, 493-501. Marchessault, R. H . ; Deslandes, Y. Carbohydr. Res., 1979, 75, 231-242.

RECEIVED May

21,

1980.


Crystal Structure of - American Chemical Society

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