Isolation and structure determination of a new lasso peptide subterisin from Sphingomonas subterranea

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Identification of a Mung Bean Arabinofuranosyltransferase That Transfers Arabinofuranosyl Residues onto (1, 5)-Linked α-l-Arabino-Oligosaccharides

Arabinofuranosyltransferase activity was identified in Golgi membranes obtained from mung bean (Vigna radiata) hypocotyls. The enzyme transfers the arabinofuranosyl (Araf) residue from UDP-β-l-arabinofuranose to exogenous (1, 5)-linked α-l-arabino-oligosaccharides labeled at their reducing ends with 2-aminobenzamide. The transferred residue was shown, using (1)H-nuclear magnetic resonance spectroscopy and α-l-arabinofuranosidase treatment, to be α-l-Araf and to be linked to O-5 of the nonreducing terminal Araf residue of the acceptor oligosaccharide. The enzyme was nonprocessive because only a single Araf residue was added to the acceptor molecule. Arabino-oligosaccharides with a degree of polymerization between 3 and 8 were acceptor substrates. The 2-aminobenzamide-labeled arabino-tetra- and pentasaccharides were the most effective acceptor substrates analyzed. The enzyme has a pH optimum between 6.5 and 7.0 and its activity is stimulated by Mn(2+) and Co(2+) ions. The apparent K(m) and V(max) values of the arabinofuranosyltransferase for UDP-arabinofuranose are 243 μm and 243 pmol min(−1) mg protein(−1), respectively. The highest enzyme activity was detected in the elongating regions of mung bean hypocotyls. The data show that UDP-arabinofuranose is the donor molecule for the generation of arabino-oligosaccharides composed of Araf residues

Identification of the Components in a <i>Vaccinium oldhamii</i> Extract Showing Inhibitory Activity against Influenza Virus Adsorption

We previously reported that extracts from plants of the Ericaceae genus Vaccinium, commonly known as the kind of blueberry, inhibited the early steps of influenza virus (IFV) infection to host cells, and that the activity was correlated with the total polyphenol content. Particularly potent inhibitory activity was observed for Vaccinium oldhamii. In this study, we identified the active components in Vaccinium oldhamii involved in the inhibition of IFV infection. We sequentially fractionated the Vaccinium oldhamii extract using a synthetic adsorbent resin column. High inhibitory activity was observed for the fractions eluted with 30%, 40%, and 50% ethanol, and three peaks (peak A, B, and C) considered to represent polyphenols were identified in the fractions by HPLC analysis. Among these peaks, high inhibitory activity was detected for peak A and B, but not for peak C. These peaks were analyzed by LC/MS, which revealed that peak A contained procyanidin B2 and ferulic acid derivatives, whereas peak B contained two ferulic acid O-hexosides, and peak C contained quercetin-3-O-rhamnoside and quercetin-O-pentoside-O-rhamnoside. It is already known that these polyphenols have anti-IFV activity, but we speculate that ferulic acid derivatives are the major contributors to the inhibition of the early steps of IFV replication, such as either adsorption or entry, observed for Vaccinium oldhamii