Measurement of three-bond coupling constants in the osmoregulated periplasmic glucan of Burkholderia solanacearum.

The cyclic osmoregulated periplasmic glucan produced by Burkholderia solanacearum contains 13 glucose units, all beta-(1-2) linked except for one alpha-(1-6) linkage. We report here the measurement of the 3J(C1-H2') and 3J(H1-C2') coupling constants, characterizing the glycosidic linkages, through the use of a 13C/12C double half-filtered NOESY experiments. The values obtained give information about the (phi, psi) angles of the different linkages. The results presented from an important step towards a detailed experimental model of the cyclic glucan, which might allow us to clarify its biological role and establish whether the cavity of these molecules is compatible with the capability of complexing host molecular signals.