n 2 + 16mgatp 2- + 8e - + 8h + → 2nh 3 + 16mgadp - + 16h 2 po 4 - + h 2
TRANSCRIPT
NN22 + 16MgATP+ 16MgATP2-2- + 8e + 8e-- + 8H + 8H++ → →
2NH2NH33 + 16MgADP + 16MgADP- - + 16H + 16H22POPO44-- + H + H22
Complex of the nitrogenase proteins stabilized by ADP-AIF4−
Howard J. B., Rees D. C. PNAS 2006;103:17088-17093
©2006 by National Academy of Sciences
Ball-and-stick representation of the nitrogenase metalloclusters
Howard J. B., Rees D. C. PNAS 2006;103:17088-17093
©2006 by National Academy of Sciences
A view of the FeMo cofactor highlighting Fe atoms 2, 3, 6, and 7 (numbering from Protein Data Bank ID code 1M1N), along with MoFe protein amino acids ligands (α-275Cys and α-442His) and
the side chains of α-195His and α-70Val
Barney B. M. et.al. PNAS 2006;103:17113-17118
©2006 by National Academy of Sciences
N NMH+
N NHM N NHM+H+
N NH2M+
N NH2M+2
H+
N NH3M+2
NH3
NM+2
2+
NM+2NM+3
NH3
1. 3H+, 6 e-
2. N2
Chatt-Type Mechanism for Single Site Catalysis
N2 + 6H+ + 6e- → 2NH3
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1859894
Proc Natl Acad Sci U S A. 2006 November 14; 103(46): 17088–17093.
How many metals does it take to fix N2? A mechanistic overview of biological nitrogen fixation
James B. Howard*† and Douglas C. Rees†‡
*Department of Biochemistry, University of Minnesota, Minneapolis, MN 55455; and
‡Division of Chemistry and Chemical Engineering, 114-96, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125
Mo
N
NN 2
Mo(VI) Terminal NitridoMo(III) Terminal ImidoMo(6), N(3x3), total = 15 Mo(6), Nimido(9), Nnitrido(3), total = 18
Mo N
NN
N
N2, 1 atm2
238K
Science, 268, 861-863
Kit Cummins Lab at MIT, 1995
Science, 268, 861-863
Kit Cummins Lab at MIT, 1995
MoN(R)Ar
N(R)Ar
Ar(R)N N2, 1 atm
238 KMo
N(R)Ar
N(R)ArAr(R)N
N
N
Mo(N(R)Ar)3
Mo
N(R)Ar
N(R)ArAr(R)N
N
N
Mo
N(R)Ar
N(R)ArAr(R)N
purple
Mo
N(R)Ar
N(R)ArAr(R)N
N
N
Mo
N(R)Ar
N(R)ArAr(R)N
Mo
N(R)Ar
N(R)ArAr(R)N
N2