Rabbit Anti-Human XG Polyclonal Antibody

Background Lytic polysaccharide monooxygenases (LPMOs) are powerful enzymes that oxidatively cleave plant cell wall polysaccharides. LPMOs classified as fungal Auxiliary Activities family 9 (AA9) have been mainly studied for their activity towards cellulose; however, various members of this AA9 family have been also shown to oxidatively cleave hemicelluloses, in particularly xyloglucan (XG). So far, it has not been studied in detail how various AA9 LPMOs act in XG degradation, and in particular, how the mode-of-action relates to the structural configuration of these LPMOs. Results TwoNeurospora crassa(Nc) LPMOs were found to represent different mode-of-action towards XG. Interestingly, the configuration of active site segments of these LPMOs differed as well, with a shorter Segment 1 ((-)Seg1) and a longer Segment 2 ((+)Seg2) present inNcLPMO9C and the opposite forNcLPMO9M ((+)Seg1(-)Seg2). We confirmed thatNcLPMO9C cleaved the non-reducing end of unbranched glucosyl residues within XG via the oxidation of the C4-carbon. In contrast, we found that the oxidative cleavage of the XG backbone byNcLPMO9M occurred next to both unbranched and substituted glucosyl residues. The latter are decorated with xylosyl, xylosyl-galactosyl and xylosyl-galactosyl-fucosyl units. The relationship between active site segments and the mode-of-action of theseNcLPMOs was rationalized by a structure-based phylogenetic analysis of fungal AA9 LPMOs. LPMOs with a(-)Seg1(+)Seg2 configuration clustered together and appear to have a similar XG substitution-intolerant cleavage pattern. LPMOs with the(+)Seg1(-)Seg2 configuration also clustered together and are reported to display a XG substitution-tolerant cleavage pattern. A third cluster contained LPMOs with a(-)Seg1(-)Seg2 configuration and no oxidative XG activity. Conclusions The detailed characterization of XG degradation products released by LPMOs reveal a correlation between the configuration of active site segments and mode-of-action of LPMOs. In particular, oxidative XG-active LPMOs, which are tolerant and intolerant to XG substitutions are structurally and phylogenetically distinguished from XG-inactive LPMOs. This study contributes to a better understanding of the structure-function relationship of AA9 LPMOs.

A hydrogel of xanthan gum (XG) was improved by crosslinking hydroxypropyl beta-cyclodextrin (HPCD) physically to construct a novel drug delivery system. This hydrogel was full of the textures due to directional self-aggregations of XG helixes observed by optical microscopy and scanning electron microscopy. Rheological measurements indicated that HPCD added into XG hydrogel affected the dynamic behaviors of the hydrogel system, and the melting point of the hydrogels also rose from 117.5 degrees C up to 125.8 degrees C due to the enhancement of the supramolecular interactions. The XG/HPCD hydrogel with mass ratios 4:3 presented more elastic network than other XG/HPCD hydrogels did, which was more suitable for drug delivery. The supramolecular interactions in the gel network were mainly hydrogen bonding by the results of Fourier transform infrared spectroscopy. X-ray powder diffraction showed the XG/HPCD xerogel with amorphous characters to the benefit of loading drugs. The drug hydrogel loading anticancer methotrexate performed an effective controlled release, reflecting a host of HPCD molecule enhanced binding of drug methotrexate. And the hydrogel loading levofloxacin also exhibited fair antibacterial effects with inhibition zone method. Hence, this XG/HPCD hydrogel obtained would be a novel and interesting drug delivery system indeed.