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Active sites and regulation of the activity of hexaheme-nitrite reductase of Desulfovibrio desulfuricans (ATCC 27774).
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Abstracts
F06I
ACTIVE SITES AND REGULATION OF THE ACTIVITY OF HEXAHEME-NITRITE REDUCTASE OF Desulfovibrio desulfuricans (ATCC 27774).
C. C o s t a a, Y. W a n g e, A. M a c e d o a, J. L e G a l l b, y . B e r l i e r b, W. Yo
Payne a, J. J. G, Moura a, B. H. Huynh c, I. M o u r a a, aC.T.Q.B and Universidade Nova de Lisboa, OeLras. Portugal,CDep. of Physics, Emory University, Atlanta, G~4 30322YDep. o f Biochemistrv, Univ. of Georgia, Athens:, GA 3036 aDep ~f Mic~obioh~g.y, Univ i~f Georgia, Athens, GA 3036
Nitrite reductase isolated from D.desulfuricans (ATCC 27774) is ~ h e x a h e m e c y t o c h r o m e that reduce nitrite to a m m o n i a a six electron red u c t i o n . EPR and M o s s b a u e r m e a s u r e m e n t s i n d i c a t e d that one of the h e m e s is high spin (S=5/2) and the other five are low spin ( S = l / 2 ) . F o u r of the hemes are magnetically coupled (low spinflow spin; high spin/low spin). Reaction of nitrite with the fully reduced enzyme reoxidizes alT the low spin heroes but leaves the high spin h e m e bound to IN(), suggesting that the high spin is the enzyme active site. Mass spectrometry revealed that the h e x a h e m e nitrite reductase from Dxiesutfi~ricans, W.succino-
genes and E.coli can 'also reduce NO (free or generated by A.cvcloclaste:~' copper enzyme) to ammonia when low potential electron donors (dithionite) are available, to N 2 0 (like denitrifiers) when high potential electron donors are present (ascorbate plus PMS).
Work supported by INIC and JNICT.
1. C. Costa, J. J. G. Moura, I. Moura, M. Y~Liu, H. D. Peck Jr,, J. LeG,all, Y.Wang and B. H, Huynh. J.Biol.Chem.265, 14382-14387 (1990). 2. C. Costa, A. Macedo, I. Moura, J. J. G. Moura, J. LeGal1, Y~ Beflier, M. Y. Liu and W. L Payne FEBSLett. 276, 67-70 (1990).
Abstracts
F06I
ACTIVE SITES AND REGULATION OF THE ACTIVITY OF HEXAHEME-NITRITE REDUCTASE OF Desulfovibrio desulfuricans (ATCC 27774).
C. C o s t a a, Y. W a n g e, A. M a c e d o a, J. L e G a l l b, y . B e r l i e r b, W. Yo
Payne a, J. J. G, Moura a, B. H. Huynh c, I. M o u r a a, aC.T.Q.B and Universidade Nova de Lisboa, OeLras. Portugal,CDep. of Physics, Emory University, Atlanta, G~4 30322YDep. o f Biochemistrv, Univ. of Georgia, Athens:, GA 3036 aDep ~f Mic~obioh~g.y, Univ i~f Georgia, Athens, GA 3036
Nitrite reductase isolated from D.desulfuricans (ATCC 27774) is ~ h e x a h e m e c y t o c h r o m e that reduce nitrite to a m m o n i a a six electron red u c t i o n . EPR and M o s s b a u e r m e a s u r e m e n t s i n d i c a t e d that one of the h e m e s is high spin (S=5/2) and the other five are low spin ( S = l / 2 ) . F o u r of the hemes are magnetically coupled (low spinflow spin; high spin/low spin). Reaction of nitrite with the fully reduced enzyme reoxidizes alT the low spin heroes but leaves the high spin h e m e bound to IN(), suggesting that the high spin is the enzyme active site. Mass spectrometry revealed that the h e x a h e m e nitrite reductase from Dxiesutfi~ricans, W.succino-
genes and E.coli can 'also reduce NO (free or generated by A.cvcloclaste:~' copper enzyme) to ammonia when low potential electron donors (dithionite) are available, to N 2 0 (like denitrifiers) when high potential electron donors are present (ascorbate plus PMS).
Work supported by INIC and JNICT.
1. C. Costa, J. J. G. Moura, I. Moura, M. Y~Liu, H. D. Peck Jr,, J. LeG,all, Y.Wang and B. H, Huynh. J.Biol.Chem.265, 14382-14387 (1990). 2. C. Costa, A. Macedo, I. Moura, J. J. G. Moura, J. LeGal1, Y~ Beflier, M. Y. Liu and W. L Payne FEBSLett. 276, 67-70 (1990).