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See detailThe Folding Process of Hen Lysozyme: A Perspective from the 'New View'
Matagne, André ULg; Dobson, Christopher M.

in Cellular and Molecular Life Sciences : CMLS (1998), 54(4), 363-71

How a conformationally disordered polypeptide chain rapidly and efficiently achieves its well-defined native structure is still a major question in modern structural biology. Although much progress has ... [more ▼]

How a conformationally disordered polypeptide chain rapidly and efficiently achieves its well-defined native structure is still a major question in modern structural biology. Although much progress has been made towards rationalizing the principles of protein structure and dynamics, the mechanism of the folding process and the determinants of the final fold are not yet known in any detail. One protein for which folding has been studied in great detail by a combination of diverse techniques is hen lysozyme. In this article we review the present state of our knowledge of the folding process of this enzyme and focus in particular on recent experiments to probe some of its specific features. These results are then discussed in the context of the 'new view' of protein folding based on energy surfaces and landscapes. It is shown that a schematic energy surface for lysozyme folding, which is broadly consistent with our experimental data, begins to provide a unified model for protein folding through which experimental and theoretical ideas can be brought together. [less ▲]

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See detailX-ray studies of enzymes that interact with penicillins.
Kelly, J. A.; Kuzin, A. P.; Charlier, Paulette ULg et al

in Cellular and Molecular Life Sciences : CMLS (1998), 54(4), 353-8

The technique of X-ray diffraction has been successfully applied to enzymes associated with peptidoglycan biosynthesis. The technique has taught us a great deal about the structures and catalytic ... [more ▼]

The technique of X-ray diffraction has been successfully applied to enzymes associated with peptidoglycan biosynthesis. The technique has taught us a great deal about the structures and catalytic mechanisms of penicillin-binding proteins and beta-lactamases. An insight into the structural basis for antibiotic resistance is given. [less ▲]

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See detailCatalytic reaction pathways approached by quantum chemistry: a challenge
Dive, Georges ULg; Dehareng, Dominique ULg; Ghosez, Léon

in Cellular and Molecular Life Sciences : CMLS (1998), 54(4), 378-382

This review explores the potential of quantum chemistry to help understand complex biochemical reactions such as enzyme catalysis. Starting from a historical background, the article introduces the reader ... [more ▼]

This review explores the potential of quantum chemistry to help understand complex biochemical reactions such as enzyme catalysis. Starting from a historical background, the article introduces the reader to the great diversity of problems than can be dealt with in the framework of quantum chemistry. [less ▲]

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See detailbeta-lactamases as models for protein-folding studies
Vanhove, M.; Lejeune, Annabelle ULg; Pain, R. H.

in Cellular and Molecular Life Sciences : CMLS (1998), 54(4), 372-377

This review traces some of the key features of the folding of beta-lactamases and their relevance to the way proteins fold in general. Studies on the enzymes have highlighted the nature and role of ... [more ▼]

This review traces some of the key features of the folding of beta-lactamases and their relevance to the way proteins fold in general. Studies on the enzymes have highlighted the nature and role of equilibrium and transient condensed states. The kinetics of folding are multiphasic, and when monitored by acrylamide quenching of the tryptophan fluorescence, an early phase provides evidence for the transient accumulation of a nonnative intermediate involving burial of tryptophan in a nonpolar environment. Intermediate phases can be understood in terms of progressive folding of different parts of the molecule. The later, slow phases are associated with proline isomerization in the TEM-1 enzyme and, in its P167T mutant form, with isomerization from trans to cis of the E166 T167 peptide bond. Coupled with kinetic and X-ray crystallographic studies of the beta-lactamase from Staphylococcus aureus and its D179Q mutant, it appears that the final stage of folding is that of collapse and packing of the Omega-loop on to the main body of the protein. [less ▲]

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See detailThe diversity, structure and regulation of beta-lactamases.
Philippon, A; Dusart, Jean; Joris, Bernard ULg et al

in Cellular and Molecular Life Sciences : CMLS (1998), 54(4), 341-6

beta-Lactamase production is responsible for the appearance of a large number of pathogenic bacterial strains exhibiting a high degree of resistance to beta-lactam antibiotics. A large number of enzymes ... [more ▼]

beta-Lactamase production is responsible for the appearance of a large number of pathogenic bacterial strains exhibiting a high degree of resistance to beta-lactam antibiotics. A large number of enzymes have been described with very diverse primary structures and catalytic profiles. Nevertheless, all known three-dimensional structures of active-site serine beta-lactamases exhibit a high degree of similarity with apparently equivalent chemical functionalities in the same strategic positions. These groups might not, however, play identical roles in the various classes of enzymes. Structural data have also been recently obtained for the zinc metallo-beta-lactamases, but the detailed catalytic mechanisms might also differ widely, depending on the enzyme studied. Similarly, the induction of the synthesis of beta-lactamases is now better understood, but many questions remain to be answered. [less ▲]

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See detailPsychrophilic Enzymes: Molecular Basis of Cold Adaptation
Feller, Georges ULg; Gerday, Charles ULg

in Cellular and Molecular Life Sciences : CMLS (1997), 53(10), 830-41

Psychrophilic organisms have successfully colonized polar and alpine regions and are able to grow efficiently at sub-zero temperatures. At the enzymatic level, such organisms have to cope with the ... [more ▼]

Psychrophilic organisms have successfully colonized polar and alpine regions and are able to grow efficiently at sub-zero temperatures. At the enzymatic level, such organisms have to cope with the reduction of chemical reaction rates induced by low temperatures in order to maintain adequate metabolic fluxes. Thermal compensation in cold-adapted enzymes is reached through improved turnover number and catalytic efficiency. This optimization of the catalytic parameters can originate from a highly flexible structure which provides enhanced abilities to undergo conformational changes during catalysis. Thermal instability of cold-adapted enzymes is therefore regarded as a consequence of their conformational flexibility. A survey of the psychrophilic enzymes studied so far reveals only minor alterations of the primary structure when compared to mesophilic or thermophilic homologues. However, all known structural factors and weak interactions involved in protein stability are either reduced in number or modified in order to increase their flexibility. [less ▲]

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