Raman spectra of fused indium and bismuth chlorides

Kenney, John T.; Powell, F. X.

doi:10.1021/j100855a003

Cited by 18 publications

(15 citation statements)

References 4 publications

(4 reference statements)

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“…For all kinetic experiments the enzyme was used after the second ammonium sulfate precipitation (0 -50 ' %, saturation). The preparations obtained usually contained (per mg of protein) 3 nmol of flavin, 25 ng-atoms (or nmol) of After the original submission of this manuscript a further paper by Kenney appeared [40] where substantially the same conclusion as reported here was reached about MalEt interaction with the enzyme.…”

Section: Elupei-inzmtd Proceduressupporting

confidence: 62%

Reactivity of the Sulfhydryl Groups of Soluble Succinate Dehydrogenase

Vinogradov¹,

Gavrikova²,

Zuevsky³

1976

Eur J Biochem

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Soluble succinate dehydrogenase prepared by butanol extraction reacts with N-ethylmaleimide according to first-order kinetics with respect to both remaining active enzyme and the inhibitor concentration. Binding of the sulfhydryl groups of the enzyme prevents its alkylation by Nethylmaleimide and inhibition by oxaloacetate. A kinetic analysis of the inactivation by alkylating reagent in the presence of succinate or malonate suggests that N-ethylmaleimide acts as a sitcdirected inhibitor. The apparent first-order rate constant of alkylation increases between pH 5.8 and 7.8 indicating a pK, value for the enzyme sulfhydryl group equal to 7.0 at 22 "C in 50 mM Trissulfate buffer. Certain anions (phosphate, citrate, maleate and acetate) decrease the reactivity of the enzyme towards the alkylating reagent. Succinate/phenazine methosulfate reductase activity measured in the presence of a saturating concentration of succinate shows the same pH-dependence as the alkylation rate by N-ethylmaleimide. The mechanism of the first step of succinate oxidation. including a nucleophilic attack of substrate by the active-site sulfhydryl group, is discussed.

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Section: Elupei-inzmtd Proceduressupporting

confidence: 62%

Reactivity of the Sulfhydryl Groups of Soluble Succinate Dehydrogenase

Vinogradov¹,

Gavrikova²,

Zuevsky³

1976

Eur J Biochem

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“…There was no significant change observed in the protein expression level of the 70-kDa protein from the post-ischemic myocardium (data not shown). It has been proposed that SQR is one of the major components in mitochondria to host protein thiols; the 70-kDa flavin subunit is known to contain reactive/regulatory thiol(s) and implicate the SQR as a host of the redox thiols (20,43). Tissue homogenates (300 g) were subjected to immunoprecipitation with anti-70-kDa monoclonal antibody, and subsequently subjected to SDS-PAGE and immunoblotted with anti-70-kDa and anti-GSH monoclonal antibodies.…”

Section: Protein S-glutathionylation Of the 70-kda Flavin Subunit Of mentioning

confidence: 99%

Mitochondrial Complex II in the Post-ischemic Heart

Chen

Chen²,

Pfeiffer

et al. 2007

Journal of Biological Chemistry

215

111

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“…Such an interaction has been suggested to be responsible for the inhibition of succinate dehydrogenase by oxaloacetate (37), which, like pyruvate, is an ␣-keto acid. Oxaloacetate associates with a sulfhydryl located within the active site of the enzyme, preventing the binding of succinate, the inhibitor malonate, or NEM (38,39). Thus, a thiohemiacetal has a regulatory function in succinate dehydrogenase, albeit inhibitory in nature.…”

Section: ␣-Keto Acid Activation Of the Cyanide-resistant Oxidasementioning

confidence: 99%

The Reaction of the Soybean Cotyledon Mitochondrial Cyanide-resistant Oxidase with Sulfhydryl Reagents Suggests That α-Keto Acid Activation Involves the Formation of a Thiohemiacetal

Umbach

Siedow

1996

Journal of Biological Chemistry

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The cyanide-resistant alternative oxidase of plant mitochondria is known to be activated by ␣-keto acids, such as pyruvate, and by the reduction of a disulfide bond that bridges the two subunits of the enzyme homodimer. When the regulatory cysteines are oxidized, the inactivated enzyme is much less responsive to pyruvate than when these groups are reduced. When soybean cotyledon mitochondria were isolated in the presence of iodoacetate or N-ethylmaleimide, the intermolecular disulfide bond did not form and the alternative oxidase was present only as a noncovalently associated dimer. N-Ethylmaleimide inhibited alternative oxidase activity, but iodoacetate was found to stimulate activity much like pyruvate, including enhancing the enzyme's apparent affinity for reduced ubiquinone. The presence of pyruvate or iodoacetate blocked inhibition of the enzyme by N-ethylmaleimide, indicating that all three compounds acted at the same sulfhydryl group on the alternative oxidase protein. The site of pyruvate and iodoacetate action was shown to be a different sulfhydryl than that involved in the redox-active regulatory disulfide bond, because iodoacetate bound to the alternative oxidase at the activating site even when the redox-active regulatory sulfhydryls were oxidized. Given the nature of the covalent adduct formed by the reaction of iodoacetate with sulfhydryls, the activation of the alternative oxidase by ␣-keto acids appears to involve the formation of a thiohemiacetal.Plant mitochondria possess a terminal cyanide-resistant alternative oxidase in the electron transport system of the inner membrane (1, 2). This oxidase reduces oxygen to water with electrons derived directly from the ubiquinone pool. Because no protonmotive force is generated during this reaction, the alternative pathway appears to be energetically wasteful (1, 2). cDNA sequences have now been reported for the nuclear-encoded alternative oxidase from several plants, two fungi, and a protozoan (2-7).1 The mature protein contains 280 -290 amino acids and migrates as a 32-35-kDa protein on SDS-PAGE gels as revealed by immunoblotting. Hydropathy analysis has led to a model in which the alternative oxidase protein is anchored to the mitochondrial inner membrane by two membrane-spanning ␣-helices, with large hydrophilic domains approximately 100 amino acids in length flanking each membrane-spanning region and extending into the mitochondrial matrix (9). In the carboxyl-terminal hydrophilic domain, just beyond the second membrane-spanning region, is a set of conserved amino acid motifs found in the family of coupled binuclear iron proteins to which methane monooxygenase belongs (9, 10). Cross-linking studies have indicated that the plant alternative oxidase exists in the membrane as a homodimer (11).As a result of a search for the role of the alternative oxidase in plant metabolism, several regulators of its activity have been identified. The amounts of alternative oxidase protein in the membrane (e.g. Refs. 12-14) and the extent of ubiquinone pool reduction (...

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Raman spectra of fused indium and bismuth chlorides

Cited by 18 publications

References 4 publications

Reactivity of the Sulfhydryl Groups of Soluble Succinate Dehydrogenase

Reactivity of the Sulfhydryl Groups of Soluble Succinate Dehydrogenase

Mitochondrial Complex II in the Post-ischemic Heart

The Reaction of the Soybean Cotyledon Mitochondrial Cyanide-resistant Oxidase with Sulfhydryl Reagents Suggests That α-Keto Acid Activation Involves the Formation of a Thiohemiacetal

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