41. Some severe diseases can depend on the presence or absence of some enzymes related to the sialic acid metabolism. 42. This gene product belongs to a family of glycohydrolytic enzymes which remove sialic acid residues from glycoproteins and glycolipids. 43. The synthesis starts in the cytosol, where N-acetylmannosamine 6 phosphate and phosphoenolpyruvate give rise to sialic acid . 44. This prevents most Siglecs from binding to other cells as mammalian cells are covered in sialic acid -containing glycans. 45. The letter G refers to ganglioside, and M is for monosialic acid as it has one sialic acid only. 46. Typically, mature human glycoproteins only contain three mannose residues buried under sequential modification by GlcNAc, galactose and sialic acid . 47. The enzyme uses a mannose derivative as a substrate, inserting three carbons from pyruvate into the resulting sialic acid structure. 48. Sialic acid can " hide " mannose antigens on the surface of host cells or bacteria from mannose-binding lectin.49. Administration of estrogen to castrated mice leads to a dose-dependent reduction of the sialic acid content of the vagina. 50. Free sialic acid possibly can help the bacterium to recognize that it has reached a vertebrate environment suitable for its colonization.
