FIGURE 4.

A and B, overlay of ¹H-¹³C HMQC spectra of serotypes 6A (black) and 6X12 (red) (A) and 6B (black) and 6X11 (red) (B). For 6X12 and 6X11, new glucose (Glc′) signals appear, indicating that their PSs are a mixture of two different RU. A, the chemical shifts (ppm) of the labeled Gal and Glc′ peaks of 6X12 and 6A overlap at 5.60 ppm, indicating that ∼75% of 6X12 RUs are identical to 6A, whereas 25% are 6C-like because they contain glucose′. B, anomeric signals of Gal and Glc′ of 6X11 and 6B overlap at 5.12 ppm, indicating that ∼40% of 6X11 RUs are identical to 6B, whereas 60% are 6D-like because they contain Glc′. C, proposed structural models of 6X12 and 6X11 PS.