Chapter 22 Biosynthesis of amino acids nucleotides and related molecules Reduction (fixation) of N into ammonia (NH3 or NH 2.Synthesis of the 20 amino acids. 3. Synthesis of other biomolecules from amino acids 4. The de novo pathways for purine and pyrimidine biosynthesis 5. The salvage pathways for purine and pyrimidine reuse
Chapter 22 Biosynthesis of amino acids, nucleotides and related molecules 1. Reduction (fixation) of N2 into ammonia (NH3 or NH4 + ) 2. Synthesis of the 20 amino acids. 3. Synthesis of other biomolecules from amino acids 4. The de novo pathways for purine and pyrimidine biosynthesis. 5. The salvage pathways for purine and pyrimidine reuse
1, The nitrogenase complex in certain bacteria(( diazotrophs,;圆氮生勒 catalyzes the conversion of N, to NH Cyanobacteria (photosynthetic) and rhizobia (symbiont) can fix N, into NH3 The reduction of n to nh, is thermodynamically favorable 3H 2NH2 4G0=-33. 5kJ/mol for the tuple bond in N, is 942 \mo ergy But kinetically unfavorable: the bond e
1. The nitrogenase complex in certain bacteria (diazotrophs,固氮生物) catalyzes the conversion of N2 to NH3 • Cyanobacteria (photosynthetic) and rhizobia (symbiont) can fix N2 into NH3 . • The reduction of N2 to NH3 is thermodynamically favorable : • N2 + 3H2 2NH3 G` o=-33.5kJ/mol • But kinetically unfavorable: the bond energy for the triple bond in N2 is 942 kJ/mol
The nitrogenase(固氮酶) complex mainly consists of two types of enzymes: the dinitrogenase and the dinitrogenase reductase The dinitrogenase(containing molybdenum thus called the MoFe protein) is a tetramer of two different subunits, containing multiple 4Fe-4S centers and two Mo-Fe clusters The dinitrogenase reductase(also called the Fe protein) is a dimer of two identical subunits, containing a single FeaS, redox center. The nitrogenase complex is highly conserved among different diazotrophs
• The nitrogenase (固氮酶) complex mainly consists of two types of enzymes: the dinitrogenase and the dinitrogenase reductase. • The dinitrogenase (containing molybdenum, thus called the MoFe protein) is a tetramer of two different subunits, containing multiple 4Fe-4S centers and two Mo-Fe clusters. • The dinitrogenase reductase (also called the Fe protein) is a dimer of two identifcal subunits, containing a single Fe4 -S4 redox center. • The nitrogenase complex is highly conserved among different diazotrophs
Cyanobacteria and Rhizobia can fix N2 into ammonia R n leg an
Cyanobacteria and Rhizobia can fix N2 into ammonia Rhizobia exist in nodules of leguminous plants