TSRI's main web site PROMISE mirror at TSRI Metalloprotein DB site Created: 7 November 1996
Last modified: 22 January 1998

Haem-thiolate proteins
Haem type Haem iron coordination Axial iron ligand(s) Formal iron oxidation states
Haem b image
Haem b
Haem-Cys image
Pentacoordinate
SgammaCys
FeII; FeIII
Cys-haem-O2 image Cys-haem-NO image
Hexacoordinate
SgammaCys;

O2, CO, NO or other ligand

FeIII
Cys-haem=O image
Hexacoordinate
SgammaCys;

O (O·)

FeIV

`Haem-thiolate proteins' [1] is the recommended collective name for a class of haemoproteins in which the haem iron fifth ligand is a thiolate group (typically of a Cys residue). A distinctive feature of haem-thiolate proteins is a Soret absorption band at around 450 nm in the CO­difference spectrum of reduced forms [2]. The class includes the following families:

3­D structures are known for a number of P450 proteins [3], chloroperoxidase from Caldariomyces fumago [4] and murine iNOS oxygenase domain [5]. Spectral studies of haemoprotein H450 [6] suggest that its haem­binding sites resemble that of the P450s. The proximal haem iron ligand mutants of myoglobin (His­93->Cys) were constructed as `model' haem-thiolate proteins [7, 8].

Haem-thiolate proteins in motif databases

PRINTS ID PRINTS AC PROSITE/BLOCKS ID PROSITE AC BLOCKS AC
-
-
 CYS_SYNTHASE PS00901 BL00901
BP450 PR00359 CYTOCHROME_P450 PS00086 BL00086
EP450I PR00463
EP450II PR00464
EP450IV PR00465
MITP450 PR00408
P450 PR00385

Haem-thiolate proteins in PROMISE

PROMISE ID Description
HAEMCPO Haem chloroperoxidase
NOS Nitric oxide synthases
P450 P450 proteins

References

  1. Nomenclature Committee of the International Union of Biochemistry (NC­IUB) (1991) Nomenclature of electron­transfer proteins. Recommendations 1989. Eur. J. Biochem. 200, 599-611.
  2. Gotoh, O. (1993) Evolution and differentiation of P­450 genes. In Omura, T., Ishimura, Y. and Fujii­Kuriyama, Y., (eds.), Cytochrome P­450. 2nd Ed., Kodansha, Tokyo, pp. 255-272.
  3. Poulos, T.L. (1995) Cytochrome P450. Curr. Opin. Struct. Biol. 5, 767-774.
  4. Sundaramoorthy, M., Terner, J. and Poulos, T.L. (1995) The crystal structure of chloroperoxidase: a heme peroxidase-cytochrome P450 functional hybrid. Structure 3, 1367-1378.
  5. Crane, B.R., Arvai, A.S., Gachhui, R., Wu, C., Ghosh, D.K., Getzoff, E.D., Stuehr, D.J. and Tainer, J.A. (1997) The structure of nitric oxide synthase oxygenase domain and inhibitor complexes. Science 278, 425-431.
  6. Svastits, E.W., Alberta, J.A., Kim, I.C. and Dawson, J.H. (1989) Magnetic circular dichroism studies of the active site structure of hemoprotein H­450: comparison to cytochrome P­450 and sensitivity to pH effects. Biochem. Biophys. Res. Commun. 165, 1170-1176.
  7. Adachi, S., Nagano, S., Ishimori, K., Watanabe, Y., Morishima, I., Egawa, T., Kitagawa, T. and Makino, R. (1993) Roles of proximal ligand in heme proteins: replacement of proximal histidine of human myoglobin with cysteine and tyrosine by site­directed mutagenesis as models for P­450, chloroperoxidase, and catalase. Biochemistry 32, 241-252.
  8. Hildebrand, D.P., Ferrer, J.C., Tang, H.L., Smith, M. and Mauk, A.G. (1995) Trans effects on cysteine ligation in the proximal His93Cys variant of horse heart myoglobin. Biochemistry 34, 11598-11605.