TERMIUM Plus^®

Fiche 1,  Justifications,  Anglais

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Model, explaining the great specificity of enzymes for their substrates, in which the enzyme has an active site complementary to the shape of the substrate. If the substrate has a different shape, it not bind.  2, fiche 1, Anglais, - lock%2Dand%2Dkey%20relationship

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One of the first important studies on the specificity of enzymes was carried out by Emil Fischer, who found that enzymes capable of hydrolyzing glycosides can distinguish between their stereoisomeric forms. In 1894 this observation led him to enunciate the principle that the substrate molecule fits the active site of the enzyme in a ... lock-and-key relationship.... Nowadays, the modified concept of transition state stabilization is gaining favor. According to this idea, it is not that the substrate is distorted but rather that the transition state makes better contacts with the enzyme than the substrate does, so that the full binding energy is not realized until the transition state is reached. Nevertheless, we shall use the term strain to cover the general situation on enzyme-transition state complementary.  3, fiche 1, Anglais, - lock%2Dand%2Dkey%20relationship

Fiche 1,  Justifications,  Français

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Modèle de complémentarité structurale évoqué par E. Fischer qui implique une structure rigide de l'enzyme, s'adaptant rigoureusement à son substrat. Cependant, les variations d'entropie, relativement élevées, observées lors de la formation du complexe enzyme-substrat, ont conduit à admettre que ce processus est accompagné de changements de conformation des molécules.  2, fiche 1, Français, - mod%C3%A8le%20clef%2Dserrure

Record number: 1, Textual support number: 1 CONT

Les enzymes montrent une grande spécificité à l'égard de leur substrat et souvent, elles n'accepteront pas de molécules apparentées dont la conformation est légèrement différente. Ceci peut s'expliquer en supposant que l'enzyme et le substrat ont une relation de clé à serrure. [...] L'enzyme possède un site actif complémentaire de la forme du substrat. Si la conformation du substrat est différente, il ne sera pas lié.  3, fiche 1, Français, - mod%C3%A8le%20clef%2Dserrure

Fiche 1,  Justifications,  Espagnol