Sirohaem

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Structural formula of the siroheme.

Siroheme ( English Siroheme ) consists of a porphyrin with a central iron atom . Sirohaem was originally discovered in 1973 as a prosthetic group NADPH -dependent sulfite reductase from E. coli and is therefore considered the first isobacterio chlorine to be discovered . It differs from the other heme in the type and number of side chains of the porphyrin. In nature, siroheme occurs as a cofactor in plant and bacterial nitrite reductases and in sulfite reductases.

biosynthesis

Sirohem is formed biochemically from uroporphyrinogen III .

Uroporphyrinogen III is also a precursor to protoporphyrin IX, which is used for chlorophyll and heme biosynthesis. Uroporphyrinogen III is methylated to dihydrosirohydrochlorin (precorrin 1) by an S-adenosylmethionine -dependent methyltransferase . After oxidation of dihydrosirohydrochlorin, sirohydrochlorin (precorrin 2) is formed, although the responsible dehydrogenase (in A. thaliana ) has yet to be identified. Finally, the incorporation of divalent iron (Fe 2+ ) creates siroheme. This reaction is catalyzed by a sirohydrochlorin ferrochelatase.

Siroheme is synthesized biochemically from uroporphyrinogen III. This reaction pathway is catalyzed by three enzymes, a methyl transferase ( A ), an oxidase ( B ) and a ferrochelatase ( C ).

See also

Individual evidence

  1. ↑ Compound - C00748 in the Kyoto Encyclopedia of Genes and Genomes
  2. ↑ LM Siegel, MJ Murphy, H. Kamin: Reduced nicotinamide adenine dinucleotide phosphate-sulfite reductase of enterobacteria. I. The Escherichia coli hemoflavoprotein: molecular parameters and prosthetic groups . In: Journal of Biological Chemistry . tape 248 , no. 1 , 1973, p. 251-264 , PMID 4144254 (English, jbc.org [PDF]).
  3. ↑ EC  1.7.7.1
  4. ↑ EC  1.7.1.4
  5. ↑ EC  1.8.99.3
  6. ↑ Y. Seki, N. Sogawa, M. Ishimoto: Siroheme as to active Catalyst in sulfite reduction . In: Journal of Biochemistry . tape 90 , no. 5 , 1981, pp. 1487-1492 , PMID 7338517 .
  7. ^ Matthew J. Murphy, Lewis M. Siegel, Shirley R. Tove, Henry Kamin: Siroheme: A New Prosthetic Group Participating in Six-Electron Reduction Reactions Catalyzed by Both Sulfite and Nitrite Reductases . In: Proceedings of the National Academy of Sciences of the United States of America . tape 71 , no. 3 , 1974, p. 612-616 , PMID 4595566 , PMC 388061 (free full text).
  8. ↑ JM Vega, RH Garrett: Siroheme: a prosthetic group of the Neurospora crassa assimilatory nitrite reductase . In: Journal of Biological Chemistry . tape 250 , no. 20 , 1975, p. 7980-7989 , PMID 126995 (English, jbc.org [PDF]).
  9. ↑ Ryouichi Tanaka, Ayumi Tanaka: Tetrapyrrole biosynthesis in higher plants . In: Annual Review of Plant Biology . tape 58 , 2007, ISSN  1543-5008 , p. 321-346 , doi : 10.1146 / annurev.arplant.57.032905.105448 , PMID 17227226 .
  10. ^ Evelyne Raux, Helen K. Leech, Richard Beck, Heidi L. Schubert, Patricio J. Santander, Charles A. Roessner, A Ian Scott, Jan H. Martens, Dieter Jahn, Claude Thermes, Alain Rambach, Martin J. Warren: Identification and functional analysis of enzymes required for precorrin-2 dehydrogenation and metal ion insertion in the biosynthesis of sirohaem and cobalamin in Bacillus megaterium. In: Biochemical Journal . tape 370 , part 2, March 2003, p. 505-516 , doi : 10.1042 / BJ20021443 , PMID 12408752 , PMC 1223173 (free full text).
  11. ↑ EC  2.1.1.107
  12. ↑ EC  1.3.1.76
  13. ↑ EC  4.99.1.4
  14. ↑ MetaCyc: siroheme biosynthesis