Archives

  • 2018-07
  • 2019-04
  • 2019-05
  • 2019-06
  • 2019-07
  • 2019-08
  • 2019-09
  • 2019-10
  • 2019-11
  • 2019-12
  • 2020-01
  • 2020-02
  • 2020-03
  • 2020-04
  • 2020-05
  • 2020-06
  • 2020-07
  • 2020-08
  • 2020-09
  • 2020-10
  • 2020-11
  • 2020-12
  • 2021-01
  • 2021-02
  • 2021-03
  • 2021-04
  • 2021-05
  • 2021-06
  • 2021-07
  • 2021-08
  • 2021-09
  • 2021-10
  • 2021-11
  • 2021-12
  • 2022-01
  • 2022-02
  • 2022-03
  • 2022-04
  • 2022-05
  • 2022-06
  • 2022-07
  • 2022-08
  • 2022-09
  • 2022-10
  • 2022-11
  • 2022-12
  • 2023-01
  • 2023-02
  • 2023-03
  • 2023-04
  • 2023-05
  • 2023-06
  • 2023-07
  • 2023-08
  • 2023-09
  • 2023-10
  • 2023-11
  • 2023-12
  • 2024-01
  • 2024-02
  • 2024-03
  • In conclusion substrate enabled effective detection of

    2019-11-06

    In conclusion, substrate enabled effective detection of L-alanylaminopeptidase activity in all Gram-negative bacteria tested here. The chromogenic substrate showed high sensitivity at a relatively low concentration (50 mgL), with no diffusion of the coloured chelate into the surrounding agar. Lack of diffusion is important as it allows colonies to be distinguished with polymicrobial cultures. Most Gram-positive bacteria were inhibited by the substrate’s toxicity which may be an advantage or a disadvantage depending on the desired application. The synthesis and evaluation of other amino-acyl derivatives of Alizarin could be of interest to target other peptidase enzymes that allow taxonomic differentiation between species of interest. Acknowledgements We thank bioMérieux SA for generous financial support and the EPSRC UK National Mass Spectrometry Facility at Swansea University for high resolution mass spectra.
    Introduction Old Yellow Enzymes (OYEs) are NAD(P)H-dependent flavin-containing enzymes able to catalyse the reduction of carbon-carbon double bonds (CC) on a wide range of α,β-unsaturated substrates [1]. OYEs were first isolated from the yeast Saccharomyces pastorianus[2] and then from other sources such as bacteria, plants and filamentous fungi [3] where they can participate to the metabolism of both endogenous and xenobiotic compounds [1]. Some OYEs are involved in the biosynthesis of fatty acids [4] or, in plants, 12-oxophytodienoate reductase (OPR) is involved in the biosynthesis of jasmonic acid, a Torin1 receptor that regulates gene expression in plant development and defense [5]. Many other OYEs are “orphans” since the physiological substrates and their role in metabolism is still unknown. However, some OYEs have attracted a lot of attention due to their ability to perform a biotechnologically important reaction, that is the stereoselective reduction of activated CC, on a wide range of substrates of different sizes [6], [7], [8]. The resulting chiral compounds are industrially relevant and therefore OYEs are very attractive as biocatalysts [9]. Among the organisms where these enzymes have been described, fungi have been shown to possess a different number of OYEs homologs in their genomes [10]. Most of the species analyzed have from 3 to 7 genes coding for these proteins. Although some of them may be pseudogenes or expressed under control of different promoters, these data suggest a possible coexistence of different isoenzymes in fungal cells. Recently, the fungus Mucor circinelloides MUT44 has been shown to be the most efficient compared to other selected fungal strains, in reducing three model substrates, cyclohexenone, α-methylcinnamaldehyde and (E)-α-methylnitrostyrene, all characterized by the presence of different electron-withdrawing groups (EWG) and different steric hindrance [11]. Ten putative sequences of OYE genes (McOYE1-10) were found in its genome by means of a BlastP analysis, in which the query was OYE1 sequence from S. pastorianus. A recent fungal OYE classification by Nizam and collaborators [10], [12] clearly showed that this class of enzymes is divided in 3 distinct groups according to the structural peculiarity (e.g. core of the active site, accessory residues, loop regions): class I, class II and class III. By applying the same analysis parameters, nine out of ten OYEs from M. circinelloides MUT44 clustered together in class I, where OYE from bacteria, yeasts, filamentous fungi, animals and plants can be found, showing a species-specific clade, whereas only McOYE10 resulted located in class II [13]. Moreover, the expression profile of the ten enzymes is different when the fungus is grown in the presence of different substrates, suggesting that the different isoenzymes could be specialized for the conversion of different molecules [13]. In such a case, the conversion potential of the fungus can be exploited for biocatalytic purposes by using only selected isoenzymes specialized for the compound of interest.