Dem IPB wird erneut ein beispielhaftes Handeln im Sinne einer chancengleichheitsorientierten Personal- und Organisationspolitik bescheinigt. Das Institut erhält zum 6. Mal in Folge das TOTAL E-QUALITY…
Die Plant Science Student Conference (PSSC) wird seit 20 Jahren im jährlichen Wechsel von Studierenden der beiden Leibniz-Institute IPK und IPB organisiert. Im Interview erläutern Christina Wäsch…
The combination of diversity generation methods and ultrahigh-throughput screening (uHTS) technologies is key to efficiently explore nature\'s sequence space and elucidate structure-function relationships of enzymes. Beneficial substitutions often cluster in a few regions and simultaneous amino acid substitutions at multiple positions (e.g., by OmniChange) will likely lead to further improved enzyme variants. An extensive screening effort is required to identify such variants, as the simultaneous randomization of four codons can easily yield over 105 potential enzyme variants. The combination of flow cytometer-based uHTS with cell-free compartmentalization technology using (w/o/w) double emulsions (InVitroFlow), provides analysis capabilities of up to 107 events per hour, thus enabling efficient screening. InVitroFlow is an elegant solution since diversity loss through a transformation of host cells is omitted and emulsion compartments provide a genotype-phenotype linkage through a fluorescence readout. In this work, a multi-site saturation mutagenesis (mSSM) and an OmniChange library with four simultaneously saturated positions in the active site of CelA2 cellulase were screened using InVitroFlow. Screening of over 36 million events, yielded a significantly improved cellulase variant CelA2-M3 (H288F/H524Q) with an 8-fold increase in specific activity compared to the parent CelA2-H288F (83.9 U/mg) and a 41-fold increased specific activity (674.5 U/mg) compared to wildtype CelA2 (16.6 U/mg) for the substrate 4-MUC (4-methylumbelliferyl-β D-cellobioside).
Publikation
Greff, A.; Porzel, A.; Schmidt, J.; Palfner, G.; Arnold, N.;Pigment pattern of the Chilean mushroom Dermocybe nahuelbutensis Garrido & E. HorakRec. Nat. Prod.11547-551(2017)DOI: 10.25135/rnp.69.17.01.027
Fruiting bodies of the Chilean mushroom Dermocybe nahuelbutenis Garrido & E. Horak (syn.: Cortinariusnahuelbutensis (Garrido & E. Horak) E. Valenz. & G. Moreno) were chemically investigated for the first time andafforded the new dimeric anthraqinone 7,7'-emodinphyscion (1) beside the know anthraquinones dermolutein (2),endocrocin (3), skyrin (4) and the dimeric pre-anthraquinone derivative flavomannin C (5). The chemotaxonomicsignificance of the pigments is discussed.
Publikation
Alresly, Z.; Lindequist, U.; Lalk, M.; Porzel, A.; Arnold, N.; Wessjohann, L. A.;Bioactive Triterpenes from the Fungus Piptoporus betulinusRec. Nat. Prod.10103-108(2016)
Phytochemical investigation of the ethyl acetate extract of the fruiting bodies from the basidiomycete Piptoporus betulinus led to the isolation of a new bioactive lanostane triterpene identified as 3 b -acetoxy-16-hydroxy-24-oxo-5α-lanosta-8- ene-21-oic acid (1). In addition, ten known triterpenes, polyporenic acid A (5), polyporenic acid C (4), three derivatives of polyporenic acid A (8, 10, 11), betulinic acid (3), betulin (2), ergosterol peroxide (6), 9,11-dehydroergosterol peroxide (7), and fomefficinic acid (9), were also isolated from the fungus. All isolated compounds were tested for antimicrobial activity against some Gram-positive and Gram-negative bacteria as well as against a fungal strain. The new triterpene and some of the other compounds showed antimicrobial activity against Gram-positive bacteria.
Publikation
Ali, N. A. A.; Wurster, M.; Arnold, N.; Lindequist, U.; Wessjohann, L.;Essential Oil Composition from Oleogum Resin of Soqotraen Commiphora kuaRec. Nat. Prod.270-75(2008)
The major constituents of the essential oil obtained by hydrodistillation from the oleogum resin of Commiphora kua Vollesen were identified by GC-MS. Sixteen constituents were detected from the essential oil, which constituted about (90.5%) of the total amount. Major constituents of the oil were α- cadinol (33.0%), g -cadinene (22.5%), d -cadinene (17.0%), isocaryophyllene (3.7%), allo-aromadendrene (2.8%), α-muurolene (2.7%), and α-humulene (2.4%). The Oil of Commiphora kua showed moderate antifungal activity against Cladosporium cucumerinum.