Flavinphosphorsäure aus Leber

Theorell, Hugo; Karrer, P.; Schöpp, K.; Frei, Patrick

doi:10.1002/hlca.193501801143

Cited by 12 publications

(5 citation statements)

References 3 publications

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“…1 Tables 2 and 3), which is consistent with the findings of Koeppe & Miller (1972) and Arron & Edwards (1979). We have previously considered the possibility that the pH-dependence of NADPH oxidation is linked to the protonation of the 2'-phosphate group a), which has a pK of 6.2-6.3 (Theorell, 1935). Such an effect has been observed with lactate dehydrogenase (Navazio et al, 1957).…”

Section: Kinetics Of Nadph Oxidationsupporting

confidence: 85%

The regulation of exogenous NAD(P)H oxidation in spinach (Spinacia oleracea) leaf mitochondria by pH and cations

Edman¹,

Ericson²,

Møller³

1985

Biochemical Journal

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Essentially chlorophyll-free mitochondria were isolated from green leaves of spinach (Spinacia oleracea L. cv. Viking II). Uncoupled oxidation of exogenous NADPH (1 mM) to oxygen had an optimum at pH 6.0, and activity was relatively low at pH 7.0, even in the presence of 1 mM-CaCl2. There was a proportional increase in the apparent Km for NADPH with decreasing H+ concentrations, suggesting that NADPH protonated on the 2'-phosphate group was the true substrate. Exogenous NADH was oxidized by oxygen with an optimum at pH 6.9. Under low-cation conditions, EGTA or EDTA (both 1 mM) had no effect on the Vmax. of NADH oxidation, although the removal of bivalent cations from the membrane surface by the chelators could be observed by use of 9-aminoacridine fluorescence. In contrast, under high-cation conditions, chelators lowered the Vmax. by about 50%O, probably due to a better approach of the negatively charged chelators to the negative membrane surface than under low-cation conditions. In a low-cation medium, the Vmax. of NADH oxidation was increased by about 50%O by the addition of cations. This was caused by a lowering of the size of the negative surface potential through charge screening. In contrast with other cations, La3+ inhibited NADH oxidation, possibly through binding to lipids essential for NADH oxidation. The apparent Km for NADH varied 6-fold in response to changes in the size of the surface potential, suggesting that the approach of the negatively charged NADH to the active site is hampered by the negative surface potential. The results demonstrate that the spinach leafcell can regulate the mitochondrial NAD(P)H oxidation through several mechanisms: (1) the pH; (2) the cation concentration in general; and (3) the concentration of Ca2+ in particular. The results also emphasize the importance of electrostatic considerations when investigating the kinetic behaviour of membrane-bound enzymes.

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Section: Kinetics Of Nadph Oxidationsupporting

confidence: 85%

The regulation of exogenous NAD(P)H oxidation in spinach (Spinacia oleracea) leaf mitochondria by pH and cations

Edman¹,

Ericson²,

Møller³

1985

Biochemical Journal

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“…It has previously been shown that "N NMR techniques yield useful information about the structure and electronic properties of free and protein-bound flavins [15,17,[29][30][31], In the case of flavins a correlation between the chemical shift of the I5N nuclei and their n-electron density seems to exist [23,291. Accordingly the resonances of pyridinc-type nitrogens " (1) and N(5) in the oxidized flavin] and of pyrrole-type nitrogens " (3) and N(10) in the oxidized flavin] have different properties. In the case of pyridine-type nitrogens the lone-pair electrons are orthogonal to the aromatic system, whereas in the case of pyrrole-type nitrogens the lone-pair electrons participate in the aromatic system of the heterocycle.…”

Section: ' ' N N M R Sludics On Old Yellow Cwzymementioning

confidence: 99%

“…It was isolated by Warburg and Christian in 1932 from brewer's yeast [I, 21. The prosthetic group of the protein was identified as F M N by Theorell [3] (for an overview on the protein see [4]). The protein consists of two subunits of about 49 kDa, each containing one molecule of FMN.…”

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confidence: 99%

Nuclear magnetic resonance studies of the old yellow enzyme

Beinert

Rüterjans

Müller³

1985

European Journal of Biochemistry

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The apoenzyme of NADPH oxidoreductase, 'old yellow enzyme', was reconstituted with specifically "N-labeled flavin mononucleotide and investigated by ' N NMR spectroscopy in the oxidized and reduced state.The results indicate (hat in (he oxidized state a hydrogen bond is formed between the N(5) atom and the apoprotein. In addition. hydrogen bonds exist between the N(l) and N(3) atoms of FMN and thc apoprotein. The resonance position ofN( 10) indicates that this atom is somewhat sp'-hybridized, i.e. lifted o u t ofthe molecular plane of thc isoalloxazine ring system.In the reduced state the N ( l ) atom is negatively charged and the N(3) atom forms a hydrogcn bond with the apoprotein. The N(10) atom in protein-bound FMN exhibits about the same hybridization state a s in free anionic reduced FMN, i.e. it is located in the plane of the isoalloxazine ring. The chemical shift of the N(5) resonance indicates that this atom is almost completely sp'-hybridized. This interpretation can also be derived from the 15N(5)-'H coupling constant. Among the flavoproteins thus fhr studied by NMR techniques, old yellow enzytne is the only protein that shows a conformation of the reduced prosthetic group with the N(5) atom lirted out of the molecular plane.'l'he isoelectric focussing properties of old yellow cnzyme and a new easy method for the preparation of the apoprotein are also reported.

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“…Al ipoxygenase is abundant in soybean seeds (SBL1) and it has been studied from early days of protein chemistry. [1] It is almostc olorless as isolated. Beginningw ith the earliest structures of lipoxygenases, ac avity with dimensions suitable for binding af attya cid, winding through ab undle composed largely of helices, has been apparent.…”

Section: Overview Of the Active Site In Lipoxygenase And Epr Studiesmentioning

confidence: 99%

EPR Spectroscopic Studies of Lipoxygenases

Gaffney

2019

Chemistry An Asian Journal

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Polyunsaturated fatty acids are sources of diverse natural, and chemically designed products. The enzyme lipoxygenase selectively oxidizes fatty acid acyl chains using controlled free radical chemistry; the products are regio‐ and stereo‐chemically unique hydroperoxides. A conserved structural fold of ≈600 amino acids harbors a long and narrow substrate channel and a well‐shielded catalytic iron. Oxygen, a co‐substrate, is blocked from the active site until a hydrogen atom is abstracted from substrate bis‐allylic carbon, in a non‐heme iron redox cycle. EPR spectroscopy of ferric intermediates in lipoxygenase catalysis reveals changes in the metal coordination and leads to a proposal on the nature of the reactive intermediate. Remarkably, free radicals are so well controlled in lipoxygenase chemistry that spin label technology can be applied as well. The current level of understanding of steps in lipoxygenase catalysis, from the EPR perspective, will be reviewed.

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Flavinphosphorsäure aus Leber

Cited by 12 publications

References 3 publications

The regulation of exogenous NAD(P)H oxidation in spinach (Spinacia oleracea) leaf mitochondria by pH and cations

The regulation of exogenous NAD(P)H oxidation in spinach (Spinacia oleracea) leaf mitochondria by pH and cations

Nuclear magnetic resonance studies of the old yellow enzyme

EPR Spectroscopic Studies of Lipoxygenases

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