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. 2021 Mar 19;12:636038. doi: 10.3389/fendo.2021.636038

Figure 3.

Figure 3

Positions of Neu5Ac residues in CHO cell-produced recombinant FSH (A) and pituitary FSH glycans (B). Top: 3D models show neutral monosaccharide carbon atoms in green. The sialic acid residue carbon atoms are shown in magenta, like the symbols in the glycan diagrams below each 3D model. The 3D models were built using the current Glycam web tool (http://glycam.org). (A) In Gonal-F® and Bemfola®, >90% of glycans at αAsn52, αAsn78, and βAsn24 are biantennary with two α2–3 linked Neu5Ac residues (the only significant variant has one Neu5Ac instead of two). The position of potential α2–6 Neu5Ac residues (which are absent in CHO cell-produced recombinant FSH preparations) in the biantennary structure shown at the right is also shown. (B) In pituitary FSH the most abundant types of glycan are the triantennary type. Two alternatives exist (11): a. all three Neu5Ac residues can be linked α2–3; b. alternatively, there can be 2 linked α2–6 and one linked α2–3. The one α2–3 linked Neu5Ac on the Galβ1-4GlcNAcβ1-2Manα1-3 branch (right) was arbitrarily placed. A diagram of each glycan is shown below to help ID the glycans. Figure courtesy of Dr. George R. Bousfield, Department of Biological Sciences, Wichita State University, Wichita, KS, USA.