EurekaMag.com logo
+ Site Statistics
References:
47,893,527
Abstracts:
28,296,643
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Spectrophotometric examination of exogenous ligand complexes of iron iii cytochrome p 450 characterization of the axial ligand trans to thiolate in the native iron iii low spin form






Journal of Biochemistry (Tokyo) 91(5): 1651-1660

Spectrophotometric examination of exogenous ligand complexes of iron iii cytochrome p 450 characterization of the axial ligand trans to thiolate in the native iron iii low spin form

The .alpha. band of the native ferric low-spin form of cytochrome P-450 is more intense than the .beta. band and this is characteristic of the cytochrome. When the native sixth ligand of P-4501, a low-spin cytochrome P-450 of rabbit liver microsomes, was replaced with an exogenous ligand, the .alpha. band diminished and the cytochrome lost the above-mentioned spectral characteristics. This indicated that the intense .alpha. band of the cytochrome was related to the nature of its sixth ligand. P-4481, a rabbit liver microsomal cytochrome P-450 which is essentially in a high-spin state, was converted to low-spin complexes upon binding with various exogenous ligands. The intensity of the .alpha. band of low-spin P-4481 derivatives increased in the order of 1-methylimidazole and pyridine complexes, 2-methylimidazole and 2-methylpyridine complexes, and lower n-alkanol complexes. This order coincided with the decreasing order of field strength of the exogenous ligands, indicating that the intensity of the .alpha. band is inversely proportional to the field strength of the sixth ligand. The absorption spectrum of the 1-propanol complex of P-4481 was essentially identical with that of native low-spin cytochrome P-450, whereas spectra of other P-4481 derivatives were superimposable on those of the corresponding P-4501 derivatives. P-4501 and metmyoglobin showed an orderly red-shift of the Soret band upon binding with pyridine, 1-methylimidazole and cyanide. The order and the degree of the red-shift of the Soret band of P-4501 were essentially the same as those of metmyoglobin, indicating that the native sixth ligand of P-4501 may resemble that of metmyoglobin, a water molecule. The native sixth ligand of ferric low-spin cytochrome P-450 is probably an oxygenous one such as water molecule or an oxy-amino acid side chain from the apoprotein.


Accession: 006460659



Related references

Yoshida, Y.; Imai, Y.; Hashimoto-Yutsudo, C., 1982: Spectrophotometric examination of exogenous-ligand complexes of ferric cytochrome P-450. Characterization of the axial ligand trans to thiolate in the native ferric low-spin form. Journal of Biochemistry 91(5): 1651-1659

Jänig, G.R.; Makower, A.; Rabe, H.; Bernhardt, R.; Ruckpaul, K., 1984: Chemical modification of cytochrome P-450 LM2. Characterization of tyrosine as axial heme iron ligand trans to thiolate. Phenobarbital-inducible isozyme cytochrome P-450 LM2 (RH, reduced-flavoprotein:oxygen oxidoreductase (RH-hydroxylating), EC 1.14.14.1) from rabbit liver microsomes has been modified with N-acetylimidazole and tetranitromethane. Up to four tyrosine...

Jaenig, G.R.; Makower, A.; Rabe, H.; Bernhardt, R.; Ruckpaul, K., 1984: Chemical modification of cytochrome p 450 lm 2 ec 1.14.14.1 characterization of tyrosine as axial heme iron ligand trans to thiolate. Phenobarbital-inducible isozyme cytochrome P-450 LM2 from rabbit liver microsomes was modified with N-acetylimidazole and tetranitromethane. Up to 4 tyrosine residues of cytochrome P-450 LM2 are accessible to O-acetylation and to nitration. N-Deme...

Scheidt W.R.; Geiger D.K.; Hayes R.G.; Lang G., 1983: Control of spin state in porphinato iron iii complexes an axial ligand orientation effect leading to an intermediate spin complex molecular structure and physical characterization of the mono clinic form of bis 3 chloro pyridine octaethyl porphinato iron iii per chlorate. The iron(III) porphyrinate [Fe(OEP)(3-Clpy)2]ClO4, which was previously reported as exhibiting a thermal spin equilibrium (S = 1/2 .dblarw. S = 5/2), is shown to have even more complex magnetic properties. A quantum-admixed intermediate-spin state...

Dawson J.H.; Andersson L.A.; Sono M., 1982: Spectroscopic investigations of iron iii cytochrome p 450 cam ligand complexes identification of the ligand trans to cysteinate in the native enzyme. An extensive series of ligand complexes of ferric [Pseudomonas putida] cytochrome P-450-CAM was examined by UV-visible absorption, magnetic circular dichroism, and EPR spectroscopy in an attempt to identify the ligand trans to cysteinate in the 6-...

White, R.E.; Coon, M.J., 1982: Heme ligand replacement reactions of cytochrome P-450. Characterization of the bonding atom of the axial ligand trans to thiolate as oxygen. Evidence of several types has accumulated that cytochrome P-450 has a thiolate anion as one of the axial ligands to heme (the fifth ligand). On the other hand, there is as yet no general agreement on the nature of the axial ligand trans to thiolat...

Sono M.; Hager L.P.; Dawson J.H., 1991: Epr investigations of exogenous ligand complexes of low spin ferric chloroperoxidase further support for endogenous thiolate ligation to the heme iron. Previous spectroscopic studies of chloroperoxidase have provided evidence for endogenous thiolate sulfur donor ligation to the central heme iron of the enzyme. This conclusion is further supported by recent DNA squence data which revealed the exis...

Sono, M.; Hager, L.P.; Dawson, J.H., 1991: Electron paramagnetic resonance investigations of exogenous ligand complexes of low-spin ferric chloroperoxidase: further support for endogenous thiolate ligation to the heme iron. Previous spectroscopic studies of chloroperoxidase have provided evidence for endogenous thiolate sulfur donor ligation to the central heme iron of the enzyme. This conclusion is further supported by recent DNA sequence data which revealed the exi...

Anonymous, 1980: Models of the cytochromes b 1 effect of substituents axial ligand plane orientation and possible axial ligand bond strain on the pyrrole proton shifts of a series of low spin mono substituted tetra phenylporphinato iron iii bis imidazole complexes

Ohno, T.; Suzuki, N.; Dokoh, T.; Urano, Y.; Kikuchi, K.; Hirobe, M.; Higuchi, T.; Nagano, T., 2001: Remarkable axial thiolate ligand effect on the oxidation of hydrocarbons by active intermediate of iron porphyrin and cytochrome P450. In order to examine the reactivity of active intermediate derived form iron porphyrins, competitive oxidations of alkane and alkene were carried out. It has been proposed that the first step of alkane hydroxylation is H atom abstraction and that o...