Characterization of crystalline linear (1→3)-α-<small>D</small>-glucan synthesized <i>in vitro</i>

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>We investigated the crystal structure and molecular arrangement of the linear (1→3)-α-<SMALL>D</SMALL>-glucan synthesized by glucosyltransferase GtfJ cloned from <I>Streptococcus salivarius</I> using sucrose as a substrate. The synthetic products had two morphologies: wavy fibril-like crystals as major and thin lamellae as minor products. Their structures were analyzed using electron microdiffraction, synchrotron X-ray powder diffraction, and solid-state <SUP>13</SUP>C NMR spectroscopy. The fibrils and lamellae had the same allomorphic form but different molecular arrangements. The wet crystals were in a hydrated form, which converted into an anhydrous form with a significant decrease in crystallinity on drying. The hydrated and anhydrous forms had an extended-chain conformation with 2/1 helix, and the hydrated form was estimated to contain one water molecule per glucose residue. The long glucan chains were folded in the fibril crystals, while the short, extended chains were arranged perpendicular to the base plane of the lamellae.</P> <P><B>Highlights</B></P> <P> <UL> <LI> (1→3)-α-<SMALL>D</SMALL>-Glucan was synthesized by recombinant glucosyltransferase sing sucrose. </LI> <LI> The synthetic products had two morphologies: wavy fibril and thin lamella. </LI> <LI> Both products had the same crystal structures but different molecular arrangements. </LI> <LI> Molecular chains were folded in the fibril but extended in the lamellar crystals. </LI> <LI> The hydrated form was converted into an anhydrous form by drying. </LI> </UL> </P>