Advanced

Comparison of chemical properties of iron, cobalt, and nickel porphyrins, corrins, and hydrocorphins

Jensen, Kasper LU and Ryde, Ulf LU (2005) In Journal of Porphyrins and Phthalocyanines 9(8). p.581-606
Abstract
Density functional calculations have been used to compare the geometric, electronic, and functional properties of the three important tetrapyrrole systems in biology, heme, coenzyme B12, and coenzyme F430, formed from iron porphyrin (Por), cobalt corrin (Cor), and nickel hydrocorphin (Hcor). The results show that the flexibility of the ring systems follows the trend Hcor > Cor > Por and that the size of the central cavity follows the trend Cor < Por < Hcor. Therefore, low-spin CoI, CoII, and CoIII fit well into the Cor ring, whereas Por seems to be more ideal for the higher spin states of iron, and the cavity in Hcor is tailored for the larger Ni ion, especially in the high-spin NiII state. This is confirmed by the... (More)
Density functional calculations have been used to compare the geometric, electronic, and functional properties of the three important tetrapyrrole systems in biology, heme, coenzyme B12, and coenzyme F430, formed from iron porphyrin (Por), cobalt corrin (Cor), and nickel hydrocorphin (Hcor). The results show that the flexibility of the ring systems follows the trend Hcor > Cor > Por and that the size of the central cavity follows the trend Cor < Por < Hcor. Therefore, low-spin CoI, CoII, and CoIII fit well into the Cor ring, whereas Por seems to be more ideal for the higher spin states of iron, and the cavity in Hcor is tailored for the larger Ni ion, especially in the high-spin NiII state. This is confirmed by the thermodynamic stabilities of the various combinations of metals and ring systems. Reduction potentials indicate that the +I and +III states are less stable for Ni than for the other metal ions. Moreover, Ni–C bonds are appreciably less stable than Co-C bonds. However, it is still possible that a Ni–CH3 bond is formed in F430 by a heterolytic methyl transfer reaction, provided that the donor is appropriate, e.g. if coenzyme M is protonated. This can be facilitated by the adjacent SO3‑ group in this coenzyme and by the axial glutamine ligand, which stabilizes the NiIII state. Our results also show that a NiIII–CH3 complex is readily hydrolysed to form a methane molecule and that the NiIII hydrolysis product can oxidize coenzyme B and M to a heterodisulphide in the reaction mechanism of methyl coenzyme M reductase. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Porphyrins and Phthalocyanines
volume
9
issue
8
pages
581 - 606
publisher
Society of Porphyrins & Phthalocyanines
external identifiers
  • wos:000235389000006
  • scopus:33244467937
ISSN
1099-1409
language
English
LU publication?
yes
id
45f7f5cb-47f8-457a-8612-bc3a0a90be9b (old id 159339)
alternative location
http://www.u-bourgogne.fr/jpp/base_article/index.php?v=09&n=08&abs=581
date added to LUP
2007-07-17 11:01:25
date last changed
2017-05-21 03:28:48
@article{45f7f5cb-47f8-457a-8612-bc3a0a90be9b,
  abstract     = {Density functional calculations have been used to compare the geometric, electronic, and functional properties of the three important tetrapyrrole systems in biology, heme, coenzyme B12, and coenzyme F430, formed from iron porphyrin (Por), cobalt corrin (Cor), and nickel hydrocorphin (Hcor). The results show that the flexibility of the ring systems follows the trend Hcor &gt; Cor &gt; Por and that the size of the central cavity follows the trend Cor &lt; Por &lt; Hcor. Therefore, low-spin CoI, CoII, and CoIII fit well into the Cor ring, whereas Por seems to be more ideal for the higher spin states of iron, and the cavity in Hcor is tailored for the larger Ni ion, especially in the high-spin NiII state. This is confirmed by the thermodynamic stabilities of the various combinations of metals and ring systems. Reduction potentials indicate that the +I and +III states are less stable for Ni than for the other metal ions. Moreover, Ni–C bonds are appreciably less stable than Co-C bonds. However, it is still possible that a Ni–CH3 bond is formed in F430 by a heterolytic methyl transfer reaction, provided that the donor is appropriate, e.g. if coenzyme M is protonated. This can be facilitated by the adjacent SO3‑ group in this coenzyme and by the axial glutamine ligand, which stabilizes the NiIII state. Our results also show that a NiIII–CH3 complex is readily hydrolysed to form a methane molecule and that the NiIII hydrolysis product can oxidize coenzyme B and M to a heterodisulphide in the reaction mechanism of methyl coenzyme M reductase.},
  author       = {Jensen, Kasper and Ryde, Ulf},
  issn         = {1099-1409},
  language     = {eng},
  number       = {8},
  pages        = {581--606},
  publisher    = {Society of Porphyrins & Phthalocyanines},
  series       = {Journal of Porphyrins and Phthalocyanines},
  title        = {Comparison of chemical properties of iron, cobalt, and nickel porphyrins, corrins, and hydrocorphins},
  volume       = {9},
  year         = {2005},
}