Fig. 1.

(A) Structures of Sia and Sia-like sugars (NulOs). Sialic acid (Neu5Ac), legionaminic acid (Leg5,7Ac₂) and pseudaminic acids (Pse5,7Ac₂ and Pse5Am7Gra) are shown. To note, Pse5Am7Gra is found as the terminal sugar of the S-layer glycan in T. forsythia ATCC 43037. For reference, the nine carbon atoms of Sia are numbered, and the structure of the NHAc group is shown in the boxed inset. (B) Schematic drawing of the structure of the S-layer O-glycan in T. forsythia ATCC 43037 (amended from Posch et al. (2011)). This figure is available in black and white in print and in color at Glycobiology online.