NANS Protein, Human (His)

NANS protein (sialic acid synthases) is an enzyme that functions in the biosynthetic pathways of sialic acids. Both subfamilies of sialic acid synthases possess N-terminal triosephosphate isomerase barrel domain and C-terminal antifreeze protein domain. Sialic acid synthases uses N-acetylmannosamine 6-phosphate and mannose 6-phosphate as substrates to generate phosphorylated forms of N-acetylneuraminic acid (Neu5Ac) and 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid (KDN), respectively. However, it exhibits much higher activity toward the Neu5Ac phosphate product. NANS catalyzes the condensation of phosphoenolpyruvate (PEP) with either ManNAc (bacteria) or ManNAc-6P (mammals) to give NeuNAc or NeuNAc-9P, respectively. NANS is related to the E. coli sialic acid synthase gene neuB, and it can partially restore sialic acid synthase activity in an E. coli neuB-negative mutant. NANS-mediated sialic acid synthesis has a pivotal role in skeletal development, specifically in growth plate cartilage. NANS mutations impair enzyme activity and lead to accumulation of N-acetylmannosamine in vivo^[1][2][3][4].