Circular Dichroism of Partially Purified Cytochrome P450 from Rabbit Liver Microsomes

The heme-related circular dichroic bands of solubilized cytochrome P450 from rabbit liver microsomes and some of its liganded derivatives were measured in the Soret region. All P450 derivatives exhibit negative circular dichroic bands in the region of the Soret absorption. The wavelengths of the dichroic bands and their ellipticities vary with ligand substitution and the oxidation state of the iron. The results are compared with CD-data from other hemoproteins and discussed with respect to stereochemical conclusions concerning the geometry and the physicochemical character of the vicinity of the heme group with regard to results obtained from other studies

Evidence of the Existence of a High Spin Low Spin Equilibrium in Liver Microsomal Cytochrome P450, and its Role in the Enzymatic Mechanism

In rabbit liver microsomal cytochrome P450 a high spin (S = = 5/2) low spin (S = 1/2) equilibrium has been proved to exist by recording temperature difference spectra in the Soret and in the visible region of the absorption spectrum of solubilized cytochrome P450. In the presence of type II substrates the predominantly low spin state of cytochrome P450 is maintained, only a very small shift to lower spin is observed. Ligands of the heme iron, such as cyanide and imidazole, pr9duce a pure low spin state and therefore in the presence of these ligands no temperature difference spectra can be obtained. In the presence of type I substrate, however, the spin equilibrium is shifted to the high spin state. The extent of this shift (1) depends on specific properties of the substrate and (2) it is generally relatively small, up to about 80/o in the case of substrates investigated so far

Evidence of the Existence of a High Spin Low Spin Equilibrium in Liver Microsomal Cytochrome P450, and its Role in the Enzymatic Mechanism

In rabbit liver microsomal cytochrome P450 a high spin (S = = 5/2) low spin (S = 1/2) equilibrium has been proved to exist by recording temperature difference spectra in the Soret and in the visible region of the absorption spectrum of solubilized cytochrome P450. In the presence of type II substrates the predominantly low spin state of cytochrome P450 is maintained, only a very small shift to lower spin is observed. Ligands of the heme iron, such as cyanide and imidazole, pr9duce a pure low spin state and therefore in the presence of these ligands no temperature difference spectra can be obtained. In the presence of type I substrate, however, the spin equilibrium is shifted to the high spin state. The extent of this shift (1) depends on specific properties of the substrate and (2) it is generally relatively small, up to about 80/o in the case of substrates investigated so far

Deposition and spectral performance of an inhomogeneous broadband wide-angular antireflective coating

The gradient index coatings and optical filters based on them are a challenge for fabrication. In a round-robin experiment basically the same hybrid antireflection coating for the visible spectral region has been deposited with three different techniques: electron beam evaporation, ion beam sputtering and radio frequency magnetron-sputtering. Spectral performances of such one-side and both-side coated samples have been compared with corresponding theoretical spectra of the designed profile. Also, reproducibility of each process is checked

Circular Dichroism of Partially Purified Cytochrome P450 from Rabbit Liver Microsomes

The heme-related circular dichroic bands of solubilized cytochrome P450 from rabbit liver microsomes and some of its liganded derivatives were measured in the Soret region. All P450 derivatives exhibit negative circular dichroic bands in the region of the Soret absorption. The wavelengths of the dichroic bands and their ellipticities vary with ligand substitution and the oxidation state of the iron. The results are compared with CD-data from other hemoproteins and discussed with respect to stereochemical conclusions concerning the geometry and the physicochemical character of the vicinity of the heme group with regard to results obtained from other studies