Spectral Similarities between “H-450” and Cytochrome P-450

Hasegawa, Tohru; Sadano, Hiroyuki; Omura, Tsuneo

doi:10.1093/oxfordjournals.jbchem.a134822

Cited by 18 publications

(25 citation statements)

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“…1, below T c the average x 2 declines with temperature due to the decrease of the Weiss field, which causes the maximum of the distribution function to shift to smaller moments. This is in agreement with earlier results 1,5,6,14,15,17 . The width of the distribution function increases with temperature, which counteracts the decrease of the local moment.…”

Section: Thermodynamic Properties: Monte Carlo and Mean-field Resupporting

confidence: 94%

“…A large amount of work has been devoted to the thermodynamics of itinerant magnets using phenomenological Ginzburg-Landau models for weak ferromagnets 1,2,3 or the Hubbard model and the functional integral methods. 1,4,5,6 These studies have clarified the role of LSF in thermodynamics and explained the observed behavior of the paramagnetic susceptibility. However, these methods are unsuitable for quantitative studies of realistic materials.…”

Section: Introductionmentioning

confidence: 94%

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Thermodynamics of itinerant magnets in a classical spin-fluctuation model

2008

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Thermodynamics of itinerant magnets is studied using a classical model with one parameter characterizing the degree of itinerancy. Monte Carlo simulations for bcc and fcc lattices are compared with the mean-field approximation and with the Onsager cavity field approximation extended to itinerant systems. The qualitative features of thermodynamics are similar to the known results of the functional integral method. It is found that magnetic short-range order is weak and almost independent on the degree of itinerancy, and the mean-field approximation describes the thermodynamics reasonably well. Ambiguity of the phase space measure for classical models is emphasized. The Onsager cavity field method is extended to itinerant systems, which involves the renormalization of both the Weiss field and the on-site exchange interaction. The predictions of this approximation are in excellent agreement with Monte Carlo results.

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Section: Thermodynamic Properties: Monte Carlo and Mean-field Resupporting

confidence: 94%

Section: Introductionmentioning

confidence: 94%

Thermodynamics of itinerant magnets in a classical spin-fluctuation model

2008

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“…Following deoxygenation [24], the sample was reduced by the addition of 5 μl of a deoxygenated saturated solution of sodium dithionite using a Hamilton gastight syringe. The success of heme iron reduction was monitored spectroscopically [25]. After the reduction was completed, the CBS activity was determined under anaerobic conditions at physiological pH 7.4.…”

Section: Nih-pa Author Manuscriptmentioning

confidence: 99%

Purification and characterization of the wild type and truncated human cystathionine β-synthase enzymes expressed in E. coli

Frank

Kent

Meier

et al. 2008

Archives of Biochemistry and Biophysics

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In this paper, we describe the expression and characterization of recombinant human cystathionine β-synthase (CBS) in Escherichia coli. We have used a glutathione-S-transferase (GST) fusion protein vector and incorporated a cleavage site with a long hinge region which allows for the independent folding of CBS and its fusion partner. In addition, our construct has the added benefit of yielding a purified CBS which only contains one extra glycine amino acid residue at the Nterminus. In our two-step purification procedure we are able to obtain a highly pure enzyme in sufficient quantities for crystallography and other physical chemical methods. We have investigated the biochemical and catalytic properties of purified full-length human CBS and of two truncation mutants lacking the Cterminal domain or both the N-terminal heme-binding and the C-terminal regulatory regions. Specifically, we have determined the pH optima of the different CBS forms and their kinetic and spectral properties. The full-length and the C-terminally truncated enzyme had a broad pH 8.5 optimum while the pH optimum of the N-and C-terminally truncated enzyme was sharp and shifted to pH 9. Furthermore, we have shown unequivocally that CBS binds one mole of heme per subunit by determining both the heme and the iron content of the enzyme. The activity of the enzyme was unaffected by the redox status of the heme iron. Finally, we show that CBS is stimulated by S-adenosyl-L-methionine but not its analogs. KeywordsHomocystinuria; S-adenosylmethionine; Pyridoxal-5′ phosphate; Heme Cystathionine β-synthase (CBS) 2 (L-Serine hydrolyase (adding homocysteine), EC 4.2.1.22) is central to sulfur amino acid metabolism in eukaryotes, and complete CBS deficiency is the principal cause of homocystinuria in humans. The CBS-catalyzed condensation of serine and homocysteine generates cystathionine which is then cleaved with cystathionine γ-lyase (CGL) to yield cysteine [1].Cysteine synthase (O-acetylserine sulfhydrase, OASS; CS), the CBS counterpart in prokaryotes, plants and enteric protozoa, catalyzes the formation of cysteine from Oacetylserine and hydrogen sulfide (H 2 S) with the concomitant release of acetic acid. Unlike mammals, these organisms are able to assimilate inorganic sulfur into organic sulfur and are therefore essential players in the sulfur cycle in nature. CS and CBS are affiliated with the large β-family of pyridoxal-5′-phosphate (PLP) dependent enzymes and have a high degree * Corresponding author. Fax: +1 303 724 3838. Jan.Kraus@UCHSC.edu (J.P. Kraus). 1 These authors contributed equally to this work.2 Abbreviations used: CBS, Cystathionine β-synthase; GST, glutathione S-transferase; PLP, pyridoxal 5′-phosphate; AdoMet, Sadenosyl-L-methionine; CS, cysteine synthase; OASS, O-acetylserine sulfhydrase; β-gal, β-galactosidase; OAS, O-acetyl serine; AdoHcy, S-adenosylhomocysteine. CBS is the only PLP dependent enzyme which contains heme [7]. The heme is co-ordinated by Cys 52 and His 65 residues located in the N-terminal region of the enzym...

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“…It is rather astonishing that all the characters which make Ni a model of itinerant ferromagnetism amount finally t o the addition of a T-independent Pauli-like susceptibility xo. Perhaps this has to do with the fact that in Ni the spin length above Tc is only weakly temperature-dependent [20], so that it closely resembles the behavior of localized spin models. Fig.…”

Section: Otdered Ferronragnetsmentioning

confidence: 99%

The Generalized Curie‐Weiss Law

Fähnle

Souletie²

1986

Physica Status Solidi (b)

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It is shown that the zero-field suscetpibility x of many ferromagnets may be described with high accuracy by a modified power law (generalized Curie-Weiss law) xT -[ ( T -Tc)/T]-vc in the whole paramagnetic regime, where yc is the critical susceptibility exponent. In contrast, the conventional power law z T c -[ ( T -Tc)/Tc]-vc holds only for the very small critical regime. Application of the scaling variable (T -T c ) / T , which is non-linear in T , to other physical situations (spin glasses, percolation) is discussed. Altogether the temperature range where scaling ideas ere useful appears to be much wider than generally expected. Es wird gezeigt, daR die The Generalized Curie-Weiss LawSuppose an experimentalist investigating the paramagnetic zero-field susceptibility x ( T ) of a ferromagnet near the Curie temperature T c is asking: "How can I determine the extension of the critical regime ?" The conventional answer is: "The critical regime is the one for which the susceptibility data may be represented t o a certain accuracy bywhere yc is the asymptotic critical exponent". To test for the validity of (l), Kouvel and Fisher [l]

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Spectral Similarities between “H-450” and Cytochrome P-450

Cited by 18 publications

References 0 publications

Thermodynamics of itinerant magnets in a classical spin-fluctuation model

Thermodynamics of itinerant magnets in a classical spin-fluctuation model

Purification and characterization of the wild type and truncated human cystathionine β-synthase enzymes expressed in E. coli

The Generalized Curie‐Weiss Law

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