Mushrooms and their use

Peck, Charles H.

doi:10.5962/bhl.title.3904

Cited by 20 publications

(33 citation statements)

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“…[Se]FDHH is produced by Escherichia coli grown under anaerobic conditions in the absence of added electron acceptors (15). This selenoenzyme is a component of the formate hydrogen lyase complex, which decomposes formate to carbon dioxide and molecular hydrogen (16,17).…”

mentioning

confidence: 99%

Catalytic properties of an Escherichia coli formate dehydrogenase mutant in which sulfur replaces selenium.

Axley

Böck

Stadtman

1991

Proc. Natl. Acad. Sci. U.S.A.

220

165

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Formate dehydrogenase H ofEscherichia coli contains selenocysteine as an integral amino acid. We have purified a mutant form of the enzyme in which cysteine replaces selenocysteine. To elucidate the essential catalytic role of selenocysteine, kinetic and physical properties of the mutant enzyme were compared with those of wild type. The mutant and wild-type enzymes displayed similar pH dependencies with respect to activity and stability, although the mutant enzyme profiles were slightly shifted to more alkaline pH. Both enzymes were inactivated by reaction with iodoacetamide; however, addition of the substrate, formate, was necessary to render the enzymes susceptible to alkylation. Alkylation-induced inactivation was highly dependent on pH, with each enzyme displaying an alkylation vs. pH profile suggestive of an essential selenol or thiol. Both forms of the enzyme use a ping-pong bi-bi kinetic mechanism. The mutant enzyme binds formate with greater affinity than does the wild-type enzyme, as shown by reduced values of Km and Kd. However, the mutant enzyme has a turnover number which is more than two orders of magnitude lower than that of the native selenium-containing enzyme. The lower turnover number results from a diminished reaction rate for the initial step of the overall reaction, as found in kinetic analyses that employed the alternative substrate deuterioformate. These results indicate that the selenium of formate dehydrogenase H is directly involved in formate oxidation. The observed differences in kinetic properties may help explain the evolutionary conservation of selenocysteine at the enzyme's active site.

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confidence: 99%

Catalytic properties of an Escherichia coli formate dehydrogenase mutant in which sulfur replaces selenium.

Axley

Böck

Stadtman

1991

Proc. Natl. Acad. Sci. U.S.A.

220

165

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“…Through winter 1951, 180 skiers joined the STA. The lodge was such a success that Anton, 'who was not prepared to sit back, even for a short time' , 109 launched another hut building project. As early as November 1951, the STA chose a site for a new venture in Kunama Valley.…”

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confidence: 99%

“…127 Austria retained a special position in the heart of 'fairly anglicized' Charles Anton. 128 His life shows an interesting contradiction between his pride in being assimilated and his embrace of Austrian cultural paraphernalia. On the one hand, Anton never spoke much to friends about his past in Austria.…”

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confidence: 99%

Migration, Knowledge Transfer, and the Emergence of Australian Post-War Skiing: The Story of Charles William Anton

Strobl

2016

The International Journal of the History of Sport

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faculty of health, arts and Design, swinburne university of Technology, hawthorn, australia ABSTRACT Skiing underwent substantial changes during the post-war years when the sport turned into a multi-billion dollar industry and a leisure activity for the masses. Despite its global nature and popularity, skiing in academic writing has not gained much recognition. This paper explores the role of knowledge transfer during the pioneering phase of post-war skiing in Australia. It describes the life of Charles William Anton, an Austrian refugee from the Anschluss who migrated to Sydney and subsequently became one of the founding fathers of Australian post-war skiing. The following pages show the multi-layered nature of skiing as a global sport by exemplifying how ideas spread from prewar Europe to post-war Australia. The paper will also provide a case study about refugee knowledge transfer and the 'productive process of absorption, adoption or rejection of knowledge' that takes place once an idea has been introduced into a new environment.The difficulties of building in such a remote and inaccessible spot are forbidding. Experts said it couldn't be done. One man thought differently. He was Mr. Charles Anton.

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“…The hydrogen production activity of hydrogenases is most commonly determined by measuring hydrogen evolution during the oxidation of a dithionite-reduced electron carrier [2]. Excess dithionite is required to maintain a constant level of reduced electron carrier and a low redox potential so that the amount of hydrogen produced is linear with time.…”

Section: Theorymentioning

confidence: 99%

“…The concentrations of dithionite and (bi)sulphite determine the redox potential of the dithionite/(bi)sulphite redox couple according to Eqn (2).…”

Section: Mathematical Ikscriptioii Of Scheme I Before Addition Of Hydmentioning

confidence: 99%

An Analysis of Activity Determinations in a Series of Coupled Redox Reactions with Special Reference to Hydrogenase

Dijk

Mayhew

Veeger

1981

European Journal of Biochemistry

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In this paper a spectrophotometric method is described to study the effects of pH and redox potential on the hydrogen production activity of hydrogenase, which will be applied in the following paper.The theoretical part of this paper gives the mathematical description of a system in which a redox mediator is continuously reduced by a redox system, in a non-rate-limiting way and continuously enzymatically oxidized, in a rate-limiting way. Due to the changes in redox potential during the course of the reaction the ratio reduced/ oxidized redox mediator declines gradually. It is possible to relate the changes in this ratio to the actual amount of product formed.The calculation of product formation has been applied to the production of hydrogen by hydrogenase in a system with a redox mediator, whose reduced form functions as the ultimate electron donor for hydrogenase, and the dithionite/(bi)sulphite redox couple as reducing system. The changes in the ratio reduced/oxidized redox mediator as a function of pH and redox potential, followed spectrophotometrically, have been related to the hydrogen production activity of hydrogenase.The second part of the paper deals with the analysis of the theory and describes the conditions under which the method can be used with methyl viologen as redox mediator.The conditions for determining the pH dependence of the hydrogen production activity manometrically are also described.In general, hydrogenases catalyze the overall reaction 2 H C + 2 e 2 HZ.(1) The hydrogen evolution activity of hydrogenase is most commonly determined by following hydrogen formation in the presence of an electron carrier and an excess of dithionite ion to maintain a constant level of the reduced form of the electron carrier and a low redox potential. Since firstly, besides a reduced electron carrier, protons are also a substrate for hydrogenase and secondly, hydrogenase is a redox enzyme, the effects of pH and redox potential on the hydrogen production activity at a constant concentration of reduced electron carrier are of particular interest. As has been shown by Mayhew [l], however, the reducing capacity of dithionite is pH-dependent and decreases with decreasing pH, which results in a decreased concentration of reduced electron carrier at low pH values, thus interfering with the measurements of pH-dependent and redox-potential-dependent hydrogen production activity.In this paper we describe the theoretical aspects and practical details of a spectrophotometric method to determine the hydrogen production activity as a function of pH and redox potential, as well as certain limitations of the manometric assay.The methods and conditions described in this paper will be applied in the following paper, which gives detailed infor- mation about the effects of pH and redox potential on the hydrogen production activity of the hydrogenase from Megasphaera elsdenii. THEORYThe hydrogen production activity of hydrogenases is most commonly determined by measuring hydrogen evolution during the oxidation of a dithionite-re...

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Mushrooms and their use

Cited by 20 publications

References 0 publications

Catalytic properties of an Escherichia coli formate dehydrogenase mutant in which sulfur replaces selenium.

Catalytic properties of an Escherichia coli formate dehydrogenase mutant in which sulfur replaces selenium.

Migration, Knowledge Transfer, and the Emergence of Australian Post-War Skiing: The Story of Charles William Anton

An Analysis of Activity Determinations in a Series of Coupled Redox Reactions with Special Reference to Hydrogenase

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