Extrait remanié de: Thèse 3e cycle--Biochimie--Lille I, 1973. N°: 382. / Extraits de "F.E.R.S. Letters". Vol. 15. June 1971. 2, pp. 116-117 et de European journal of biochemistry. Vol. 27. 1972, pp. 585-592.

FlgJ belongs to Carbohydrate Active enZyme (CAZy) family GH73 and facilitates passage of the bacterial flagellum through the peptidoglycan (PG) layer by cleaving the glycosidic bonds within glycan strands of PG. In this thesis I present the structure of the GH73 enzyme FlgJ from bacterial pathogenSalmonella typhimurium (St FlgJ). The St FlgJ active site was found to be blocked by the C-terminus of a neighbouring symmetry mate. To investigate if the C-terminus of FlgJ inhibits enzymatic activity similarly to the N-terminus of GH73 enzyme Auto, the glycolytic activity of St FlgJ was measured with and without its C-terminus. The assays revealed St FlgJ activity to be unaffected by the presence of the C-terminal sequence. Removal of the C-terminus did, however, allow a crystal structure of the domain to be obtained where a β-hairpin known to accommodate critical catalytic residues was found capable of opening widely, which likely aids in substrate capture and turnover. / February 2016

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A photoelectron (PE) spectrometer has been modified to study unstable molecules. Reconstruction of the ionization chamber has made the ionization region more easily accessible, and a quadrupole mass spectrometer has been added in order to provide mass spectral identification data under the same conditions as the PE experiment. The system is controlled by a LSI 11/03 microcomputer with suitable interfacing hardware. A real-time operating system program has been developed for data handling. Light sources such as the HLc (Hydrogen Lyman a line, l0.2eV) and HL[sub=αβƴ] (a mixture of Hydrogen Lyman α, β and ƴ lines) radiations were used to reduce ion-fragmentation. Pure S₄N₄, S₄N₂, S₃N₃ and S₂N₂ were synthesized and studied with this system. The interrelationship between the gas phase reactivities of these compounds has been established. The study of CH₃NO, its trans and cis dimers, and its isomer, CH₂NOH, has clarified some mistakes in species identification in previous PE spectroscopic work on CH₃NO and its dimers. These two studies illustrate our ability to identify unstable species even in a very complex mixture with this system. A cryopump was constructed and may be positioned close to the ionization region opposite to the sample inlet, which may be a fine nozzle. This fast pumping nozzle system has been used to produce nearly pure N₂0, and a charge-transfer complex (CH₃)₂0-BF₃, and excellent PE spectra of these species were obtained. A library of computer programs has been established which provides a wide variety of quantum mechanical computations applicable to PE band assignments. These programs, such as CNDO/2, MINDO/3, MNDO, HAM/3, GAUSSIAN 70 and 76, and RSPT (for perturbation corrections to Koopmans' theorem), were used throughout this work and their accuracy and efficiency assessed. Koopmans' theorem has been shown to break down if applied to the ionization of CH₃NO and N₂O₄. Moreover, shake-up processes in the Hel region have been studied for these two molecules and S₄N₂. Several of the molecules, such as S₄N₂, S₃N₃ and (CH₃)₂0-BF₃, have not been investigated by PE spectroscopy before. / Science, Faculty of / Chemistry, Department of / Graduate

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published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

Thesis--University of California, Berkeley, 1959. / "Chemistry-General" Includes bibliographical references (p. ).

Tippler structures operate under arduous conditions for most of their operational lives. During routine structural inspections large fatigue cracks were discovered on some of the main structural components of a Tippler structure. These cracks were situated in a safety-critical area of the structure and therefore rendered the structure unsafe for operation. Structural failure could affect throughput enormously as the Tippler forms the first step in a coal terminal’s operational process. A high operational availability is therefore expected from these structures. The complex rotational working of the Tippler structure complicates the analytical evaluation of the structure. A further complication is the ever-changing boundary conditions while the structure rotates, together with the weight reduction of the coal in the wagons when the wagons are offloaded. Both these factors need to be taken into account when determining the stress levels in the structure while operational. This study identifies the main factors that led to the development of the structural cracks. The analysis process consisted of constructing a linear static finite element model of the Tippler structure and verifying the accuracy of the model by means of strain gauge measurements on the actual structure. From this analysis accurate stress values were obtained for the structure under operational conditions. A short literature study identified additional factors that would have an effect on the fatigue life of the structure under the conditions as experienced at a coal terminal. In the last part of the study the information obtained form the analysis and literature sources were applied to verify the suitability of the proposed changes made to the structure. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / MEng / unrestricted

No description available.