Protons reduced

Roy F, E Samain, HC Dubourguier, G Albagnac (1986) Synthrophomonas (sic) sapovorans sp. nov., a new obligately proton reducing anaerobe oxidizing satnrated and unsatnrated long chain fatty acids. Arch Microbiol 145 142-147. 

Guangsheng C, CM Plugge, W Roelofsen, FP Houwen, AIM Stams (1992) Selenomonas acidaminovorans sp. nov., a versatile thermophilic proton-reducing anaerobe able to grow by decarboxylation of succinate to propionate. Arch McrohioZ 157 169-175. 

At present, several stable photocatalytic systems for production of hydrogen from water and organic compounds are made of semiconducting oxides and suitable proton reducing catalyzer. An efficient electron transfer between inorganic semiconductor and bacterial hydrogenase was shown to result in hydrogen photoproduction. 

The acidity constants calculated from every point in the titration curve (Figure 2.2a and b) are microscopic acidity constants (Eqs. 2.5, 2.6). Each loss of a proton reduces the charge on the surface and thus affects the acidity of the neighboring... 

In the case of muonic hydrogen rur in (3.30) is the muon-proton reduced mass. 

Interconversions in the hoot family, which includes the boat, twist-boat, and boat-boat forms, have been extensively discussed by Hendrickson and by Roberts and coworkers. The twist-boat is calculated to be of lowest energy in this family and it also has the lowest S5unmetry, having four different sets of isochronous protons. Interconversion with the boat-boat, which has only three different sets of isochronous protons, reduces the four sets to three, and the time-average S5mimetry becomes the same as that of the boat-boat form. The boat-boat form has 8 isoclinal protons on alternate carbons, and 4 axial and 4 equatorial protons situated in pairs, also on alternate carbons. This form is calculated to be the transition state for the interconversion of two twist-boats, and the activation energy is therefore only 0.5 kcal/mole (Table 2). Thus, for cyclooctane itself, twist-boat forms will interconvert extremely rapidly with one another, such that for nmr purposes the symmetry will appear the same as that of the boat-boat form, even at — 200 °C. 

The replacement of the N-methyl group with a proton reduces activity but does not eliminate it. The secondary NH group is more polar than the tertiary AT-methyl group and therefore finds it more difficult to cross the blood-brain barrier, leading to a drop in activity. The fact that significant activity is retained despite this shows that the methyl substituent is not essential to activity. 

In the first of these, by Spilners and Smoluchowski (47, 48), a heavy irradiation with 350-mev protons reduced the catalytic activity of copper for the decomposition of formic acid by about a factor of 2 at 175° and the activation energy from 27 to 13 kcal/mole. Since the catalyst was a metal, no convenient markers were available for defects, and their presence and alteration had to be inferred, partly from the catalytic results and partly from radiation-damage theory. 

Beckett and coworkers have also discovered that protonation reduced the population of the conformer with C5-axial methyl to less than 50 % of the total [5-7]. Only the conformers 5a and 5b (5a 5b = 43 57) were detected in the case of the N-ethyl salt 5. The increased interaction of the C5-axial-methyl group with the axial hydrogen atom on the nitrogen as against the electron pair orbital in 4a is considered as the primary cause for the observed shift in the conformer distribution. The conformers 5c and 5d are destabilized due to severe 1,3-diaxial interactions as shown. The conformer 5d is destabilized by A(1,2) strain as well. 

The kinetics of the oxidations of Chromatium vinosum HIPIP by several ferrocenium derivatives show no inhibitions by charged redox-inactive metal complexes, and display a pH dependence (pK = 6.90) in which protonation reduces the HIPIP reactivity by a factor of two. Electron transfer at an uncharged hydrophobic patch near Cys-46 (4 A from the Fe4S4 core to the surface), enhanced by deprotonation of His-42, is inferred from the data. The self-exchange rate constant for the HIPIPo/HIPIPr couple is estimated to be 5 x 10 s from... 

Gardner JM, Beyler M, Kamahl M, Tschierlei S, Ott S, Hammarstrom L (2012) Light-driven electron transfer between a photosensitizer and a proton-reducing catalyst Co-adsorbed to NiO. J Am Chem Soc 134(47) 19322-19325. doi 10.1021/ja3082268... 

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