Assuntos
Tuberculose Latente , Migrantes , Inglaterra , Humanos , Programas de Rastreamento , Pesquisa QualitativaRESUMO
A large strain collection comprising antagonistic bacteria was screened for novel detergent proteases. Several strains displayed protease activity on agar plates containing skim milk but were inactive in liquid media. Encapsulation of cells in alginate beads induced protease production. Stenotrophomonas maltophilia emerged as best performer under washing conditions. For identification of wash-active proteases, four extracellular serine proteases called StmPr1, StmPr2, StmPr3 and StmPr4 were cloned. StmPr2 and StmPr4 were sufficiently overexpressed in E. coli. Expression of StmPr1 and StmPr3 resulted in unprocessed, insoluble protein. Truncation of most of the C-terminal domain which has been identified by enzyme modeling succeeded in expression of soluble, active StmPr1 but failed in case of StmPr3. From laundry application tests StmPr2 turned out to be a highly wash-active protease at 45°C. Specific activity of StmPr2 determined with suc-L-Ala-L-Ala-L-Pro-l-Phe-p-nitroanilide as the substrate was 17±2U/mg. In addition we determined the kinetic parameters and cleavage preferences of protease StmPr2.
Assuntos
Proteínas de Bactérias/biossíntese , Escherichia coli/metabolismo , Proteínas Recombinantes/biossíntese , Serina Proteases/biossíntese , Stenotrophomonas maltophilia/enzimologia , Alginatos/química , Animais , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Meios de Cultura/metabolismo , Detergentes/química , Escherichia coli/genética , Espaço Extracelular/metabolismo , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Insulina/metabolismo , Leite/metabolismo , Dados de Sequência Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Serina Proteases/química , Serina Proteases/genética , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Stenotrophomonas maltophilia/genéticaRESUMO
Oligomers and polymers (film, fabrics) of the linear aromatic polyester poly(trimethylene terephthalate) (PTT) were treated with polyesterases from Thermomyces lanuginosus, Penicillium citrinum, Thermobifida fusca and Fusarium solani pisi. The cutinase from T. fusca was found to release the highest amounts of hydrolysis products from PTT materials and was able to open and hydrolyse a cyclic PTT dimer according to RP-HPLC-UV detection. In contrast, the lipase from T. lanuginosus also showed activity on the PTT fibres and on bis(3-hydroxypropyl) terephthalate (BHPT) but was not able to hydrolyse the polymer film, mono(3-hydroxypropyl) terephthalate (MHPT) nor the cyclic dimer of PTT. As control enzymes inhibited with mercury chloride were used. Surface hydrophilicity changes were investigated with contact angle measurements and the degree of crystallinity changes were determined with DSC.
Assuntos
Esterases/química , Proteínas Fúngicas/química , Polietilenotereftalatos/química , Polímeros/química , HidróliseRESUMO
Laccases could prevent fabrics and garments from re-deposition of dyes during washing and finishing processes by degrading the solubilized dye. However, laccase action must be restricted to solubilized dye molecules thereby avoiding decolorization of fabrics. Chemical modification of enzymes can provide a powerful tool to change the adsorption behaviour of enzymes on water insoluble polymers. Polyethylene glycol (PEG) was covalently attached onto a laccase from Trametes hirsuta. Different molecular weights of the synthetic polymer were tested in terms of adsorption behaviour and retained laccase activity. Covalent attachment of PEG onto the laccase resulted in enhanced enzyme stability while with increasing molecular weight of attached PEG the substrate affinity for the laccase conjugate decreased. The activity of the modified laccases on fibre bound dye was drastically reduced decreasing the adsorption of the enzyme on various fabrics. Compared to the 5 kDa PEG laccase conjugate (K/S value 47.60) the K/S value decreased much more (47.96-46.35) after the treatment of dyed cotton fabrics with native laccase.
Assuntos
Basidiomycota/metabolismo , Celulose/química , Lacase/química , Adsorção , Cromatografia , Cromatografia em Gel , Corantes/farmacologia , Gossypium/química , Cinética , Polietilenoglicóis/química , Polímeros/química , Indústria Têxtil , TêxteisRESUMO
Amplitude contrast of images of weak phase and amplitude objects can be strengthened almost twice as compared to standard light-pole contrast by means of shadow method of image formation without special contrasting of the objects. In spite of the contour effects (electron-microscopic attenuation) appearing at image formation by asymmetrical shadow method, the quantitative interpretation of such image is quite possible. The symmetrical shadow image (image with cone illumination) is more complexly realized than the asymmetric one, but it has some additional advantages. Particularly efficient suppression of background noises is there possible. Several symmetrical shadow images can be synthetized by the differential method with or without colour coding into the final image with the signal/noise ratio increased by an order.
