The involvement of dynamical fluctuations in driving enzymatic processes is widely accepted. With respect to NQM tunnelling enzymes, the role of promoting motions in facilitating hydrogenic transfers is well studied. Few studies have however, specifically attributed, dedicated dynamical fluctuations characterised by their timescales and magnitudes, as a function of a reaction coordinate, to specific groups in a protein system. An effectively full suite of backbone resonance assignments were obtained for PETNR and on relevant ligand complexes. This provided an essential platform on which residue specific, backbone amide fluctuations were assessed. This thesis documents the application of pressure up to 1500 bar, in tandem with high resolution TROSY based NMR analysis, as a means of studying residue specific, conformer exchange perturbations. Residue specific amide compression profiles of the PETNR:FMN free enzyme system, and complexes with progesterone and tetrahydropyridine dinucleotides have been obtained. The binding of progesterone appears to induce conformational tightening of residues within the active site vicinity. The complexation of PETNR:FMN with tetrahydropyridine dinucleotides, appears to stimulate conformational shifts towards intermediate, and in some cases, slow exchange regimes in multiple residues about the active site vicinity. This is evidenced by extensive intensity attenuation of 1H-15N TROSY resonances, on the binding of tetrahydropyridine dinucleotides at 1 bar pressure, and on going from 1 bar to 1500 bar pressure. Multiple regions of sequence, spatially clustering about the active site vicinity within a 10 Å sphere of the FMN binding pocket, display appreciable sensitivity to ligand binding. Differential responses of residues to the application of high pressure between complexes was noted within segments of these regions. A region of sequence, named the β-hairpin flap displays significant differential compression profiles between the PETNR:FMN free enzyme system, and associated progesterone and tetrahydropyridine dinucleotide complexes. A role in mediating ligand engagement is proposed for R130 and R142 in the β-hairpin flap. A central hydrogen bonding network, perhaps constituting a putative proton wire in the active site of the PETNR:FMN:Progesterone complex, has been identified that could enable the shuttling of protons following catalytic protonation of oxidative substrate. The resonance response behaviour of G185 acts as a sensitive reporter on the formation of these interactions, revealed by an interrogation of the differences in chemical shift changes on progesterone binding, and in response to high pressure. The recruitment of high resolution crystallographic data sets readily supported a structural and dynamical interpretation of the observed chemical shift responses to ligand binding at 1 bar pressure, and on the application high pressure. A definitive atomistic identification of fast motion contribution to activation barrier compression was not obtained. Nevertheless, detailed, residue specific amide compression profiles, and shifts in backbone amide conformational exchange regimes in response to ground state ligand binding, and at high pressure, have been catalogued in the PETNR:FMN free enzyme system. These dynamical profiles in the free enzyme are contrasted against comparative, residue specific observations in analogue complexes of the oxidative and reductive half reactions of PETNR.

Ce mémoire est une analyse comparative écocritique entre Le Roman de Tristan et Iseut, composé par Joseph Bédier en 1900, et ses sources médiévales principales : les poèmes du XIIIe siècle de Béroul, de Thomas d’Angleterre, d’Eilhart d’Oberg et de Gottfried de Strasbourg. L’objectif principal de notre étude est de chercher à savoir si la perception de la Nature dans le roman de Bédier diffère de celle des textes médiévaux. Pour atteindre ce but, nous dirigeons notre attention sur les descriptions des paysages sauvages et sur les épisodes où les forces de la Nature semblent influencer le déroulement des évènements du récit. Nous analysons ces passages, et nous les comparons avec les descriptions correspondantes tirées des sources de Bédier. Nos résultats montrent que, même si la représentation de la Nature est chez Bédier loin d’être unilatérale, elle témoigne généralement d’une vue plus positive de la nature sauvage par rapport aux textes médiévaux. De ce fait, le roman de Bédier s’éloigne de la tradition médiévale, qui consiste à voir les environnements sauvages comme étant inhospitaliers et périlleux, et s’approche plutôt de la tradition romantique qui célèbre les merveilles de la Nature. / This essay is a comparative ecocritical analysis of The Romance of Tristan and Iseult, composed by Joseph Bédier in 1900, and its principal medieval sources: the thirteenth-century poems of Béroul, Thomas of Britain, Eilhart von Oberge and Gottfried von Strassburg. The overall aim of the study is to investigate how the perception of Nature in Bédier’s work differs from that in the medieval texts. To meet this aim, we turn to the textual descriptions of wild landscapes and the episodes where the forces of Nature seem to have a powerful influence on the unfolding of the events in the story. These passages are analysed and compared with the corresponding descriptions in Bédier’s sources. Our results show that, while Bédier’s portrayal of Nature is by no means one-sided, it generally displays a more positive view of Nature and wilderness than the medieval texts. In this regard, Bédier’s novel moves away from the medieval tradition of imagining wild environments as inhospitable and perilous and approaches the romantic tradition of celebrating the wonders of Nature.