In order to engineer the choline oxidase from Arthrobacter nicotianae (An_CodA) for the potential application as biological bleach in detergents, the specific activity of the enzyme toward the synthetic substrate tris-(2-hydroxyethyl)-methylammonium methylsulfate (MTEA) was improved by methods of directed evolution and rational design. The best mutants (up to 520% wt-activity with MTEA) revealed mutations in the FAD- (A21V, G62D, I69V) and substrate-binding site (S348L, V349L, F351Y). In a separate screening of a library comprising of randomly mutagenised An_CodA, with the natural substrate choline, four mutations were identified, which were further combined in one clone. The constructed clone showed improved activity towards both substrates, MTEA and choline. Mapping these mutation sites onto the structural model of An_CodA revealed that Phe351 is positioned right in the active site of An_CodA and very likely interacts with the bound substrate. Ala21 is part of an α-helix which interacts with the diphosphate moiety of the flavin cofactor and might influence the activity and specificity of the enzyme.

L'invention concerne un agent detergent ou de nettoyage liquide renfermant un polysaccharide inhibant le grisage. L'invention concerne egalement l'utilisation de l'agent detergent ou de nettoyage liquide, ainsi qu'un procede pour sa production.

Au cours d'un lavage en lave-vaisselle, les matieres plastiques peuvent subir un changement de couleur resultant de residus alimentaires a forte intensite de couleur comme par exemple le curry, le paprika, les tomates, le chou rouge, le ketchup, les carottes, lesquels sont introduits avec la vaisselle a laver dans le lave-vaisselle. L'apparition de tels changements de couleur doit etre reduite. On parvient a ceci essentiellement par l'utilisation de particules de polyamide poreuses et/ou de phyllosilicate synthetique.