Comparing different methods for olefin quantification in pygas and plastic pyrolysis oils: Gas chromatography-vacuum ultraviolet detection versus comprehensive gas chromatography versus bromine number titration.

In steam cracking, upstream pyrolysis oil hydroprocessing, and in many downstream processes, olefinic content is key to assess process performance and process safety risk associated with highly exothermic reactions. When looking to plastic pyrolysis oils as a potential feedstock, as well as downstream products such as pyrolysis gasoline (pygas), these materials contain unsaturated hydrocarbons which are not present in fossil feedstocks. Pygas is a product of pyrolysis and exhibits a large number of chemical structural similarities with plastic pyrolysis oils, especially in terms of olefins structure.

Two EPR-detectable [4Fe-4S] clusters, N2a and N2b, are bound to the NuoI (TYKY) subunit of NADH:ubiquinone oxidoreductase (Complex I) from Rhodobacter capsulatus.

NADH:ubiquinone oxidoreductases (Complex I) contain a subunit, TYKY in the bovine enzyme and NuoI in the enzyme from Rhodobacter capsulatus, which is assumed to bind two [4Fe-4S] clusters because it contains two sets of conserved cysteine motifs similar to those found in the 2[4Fe-4S] ferredoxins. It was recently shown that the TYKY subunit is not an ordinary 2[4Fe-4S] ferredoxin, but has a unique amino acid sequence, which is only found in NAD(P)H:quinone oxidoreductases and certain membrane-bound [NiFe]-hydrogenases expected to be involved in redox-linked proton translocation [FEBS Lett. 485 (2000) 1].

Distal genes of the nuo operon of Rhodobacter capsulatus equivalent to the mitochondrial ND subunits are all essential for the biogenesis of the respiratory NADH-ubiquinone oxidoreductase.

Seven out of the 13 proteins encoded by the mitochondrial genome of mammals (peptides ND1 to ND6 plus ND4L) are subunits of the respiratory NADH-ubiquinone oxidoreductase (complex I). The function of these ND subunits is still poorly understood. We have used the NADH-ubiquinone oxidoreductase of Rhodobacter capsulatus as a model for the study of the function of these proteins.

The NuoI subunit of the Rhodobacter capsulatus respiratory Complex I (equivalent to the bovine TYKY subunit) is required for proper assembly of the membraneous and peripheral domains of the enzyme.

The nuoI gene that encodes a ferredoxin-like subunit of the Rhodobacter capsulatus Complex I (a subunit equivalent to the bovine TYKY subunit) was mutated by homologous recombination. Both a nuoI-deleted mutant (delta nuoI mutant) and a point mutant in which Cys74 was replaced by a serine (C74S mutant) proved to be completely deficient in Complex I activity. These strains were unable to grow under anaerobic photosynthetic conditions.

The iron-sulfur clusters 2 and ubisemiquinone radicals of NADH:ubiquinone oxidoreductase are involved in energy coupling in submitochondrial particles.

The behavior of ubisemiquinone radicals and the iron-sulfur clusters 2 of NADH:ubiquinone oxidoreductase (Complex I) in coupled and uncoupled submitochondrial particles (SMP), oxidizing either NADH or succinate under steady-state conditions, was studied. Multifrequency EPR spectra revealed that the two new g2 lines of the clusters 2, only observed during coupled electron transfer under conditions where energy dissipation is rate-limiting [De Jong, A. M.