Fig. 6. Time course of hydrolysis at 100 °C of Kdo₂-[4′-³²P]lipid IV_A versus mannosyl-Kdo₂-[4′-³²P]lipid IV_A.

A, the Kdo₂-[4′-³²P]lipid IV_A control. B, mannosyl-Kdo₂-[4′-³²P]lipid IV_A. The hydrolysis is carried out in sodium acetate buffer at pH 4.5 in the presence of SDS (19). The two Kdo glycosidic linkages are about equally susceptible to cleavage under these conditions, allowing discrimination between mannose addition to the outer versus the inner Kdo (19). LpcC modifies the inner Kdo as shown by the absence of unmodified Kdo-[4′-³²P]lipid IV_A during the time course of the hydrolysis of the mannosyl-Kdo₂- [4′-³²P]lipid IV_A.