HAL Id: jpa-00224298
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Submitted on 1 Jan 1984
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SALT AND WATER BINDING TO HALOPHILIC MALATE DEHYDROGENASE
G. Zaccai, E. Wachtel, H. Eisenberg
To cite this version:
G. Zaccai, E. Wachtel, H. Eisenberg. SALT AND WATER BINDING TO HALOPHILIC MALATE DEHYDROGENASE. Journal de Physique Colloques, 1984, 45 (C7), pp.C7-269-C7-269.
�10.1051/jphyscol:1984733�. �jpa-00224298�
JOURNAL
DE PHYSIQUE
Colloque C7, supplkment au n09, Tome.45, septembre 1984 page C7-269
SALT AND WATER BINDING T O HALOPHILIC MALATE DEHYDROGENASE
G. Z a c c a i , E. ~ a c h t e l * and H. ~ i s e n b e r ~ *
I n s t i t u t Laue-Langevin,
256 X , 38042GrenobLe Cedex,
F z v m c e* ~ o ~ ~ r n e r Department, The Weizmmn I n s t i t u t e of Science, Rehovot, Isrue?,
Water and o t h e r s m a l l s o l u t e m o l e c u l e s w i l l a s s o c i a t e w i t h enzymes i n s o l u t i o n t o c r e a t e a microenvironment which b e c a u s e of i n t e r f a c e i n t e r a c t i o n s w i l l b e v e r y d i f f e r e n t from b u l k s o l v e n t . Small a n g l e n e u t r o n s c a t t e r i n g s t u d i e s of h a l o p h i l i c m a l a t e dehydrogenase from H a l o b a c t e r i u m m a r i s m o r t u i have p r o v i d e d complementary i n f o r m a t i o n t o t h a t from x-ray s c a t t e r i n g and a n a l y t i c a l c e n t r i f u g a t i o n on t h e s o l u t i o n s t r u c t u r e of t h e enzyme and i t s s o l v e n t microenvironment. T h i s i s b e c a u s e of t h e v e r y d i f f e r e n t r e l a t i v e v a l u e s o f n e u t r o n s c a t t e r i n g d e n s i t y , e l e c t r o n d e n s i t y and mass d e n s i t y f o r t h e s t r u c t u r a l components of t h i s enzyme : p r o t e i n , w a t e r and s a l t . Half of t h e mass of t h e enzyme p a r t i c l e i n c o n c e n t r a t e d NaCl s o l u t i o n s ( i n which t h e enzyme i s a c t i v e ) i s made up of a s s o c i a t e d w a t e r and s a l t e q u i v a l e n t t o a 5 m o l a l N a C l s o l u t i o n . The p a r t i c l e o c c u p i e s a c o n s t a n t volume i n t h e r a n g e of 1M to5M NaC1. S t r u c t u r a l l y , i t i s a dimer w i t h b u l k s o l v e n t r e g i o n s i n between t h e s u b u n i t s . The r a d i i o f g y r a t i o n o f p r o t e i n and t h e a s s o c i a t e d w a t e r and s a l t were d e t e r m i n e d s e p a r a t e l y . T h i s work i s d e s c r i b e d i n d e t a i l i n a p a p e r s u b m i t t e d t o t h e J o u r n a l of M o l e c u l a r Biology.
