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IUPAC name 2-(Acetylamino)-2-deoxy-β-D-mannopyranose | |
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3D model (JSmol) | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.127.007 |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C8H15NO6 | |
Molar mass | 221.21 g/mol |
Melting point | 118 to 121 °C (244 to 250 °F; 391 to 394 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
N-Acetylmannosamine is a hexosamine monosaccharide. It is a neutral, stable naturally occurring compound. N-Acetylmannosamine is also known as N-Acetyl-D-mannosamine monohydrate, (which has the CAS Registry Number: 676347-48-1), N-Acetyl-D-mannosamine which can be abbreviated to ManNAc or, less commonly, NAM). ManNAc is the first committed biological precursor of N-acetylneuraminic acid (Neu5Ac, sialic acid) (Figure 1). Sialic acids are the negatively charged, terminal monosaccharides of carbohydrate chains that are attached to glycoproteins and glycolipids (glycans).
ManNAc is the first committed biological precursor of Neu5Ac.
The initiation of sialic acid biosynthesis occurs in the cytoplasm. The main substrate for this pathway is UDP-GlcNAc, which is derived from glucose. In the rate-limiting step of the pathway, UDP-GlcNAc is converted into ManNAc by UDP-GlcNAc 2-epimerase, encoded by the epimerase domain of GNE. ManNAc is phosphorylated by ManNAc kinase encoded by the kinase domain of GNE. Sialic acid becomes “activated” by CMP-sialic acid synthetase in the nucleus. CMP-sialic acid acts as a sialic acid donor to sialylate glycans on nascent glycoproteins and glycolipids in the Golgi apparatus; it also acts as a cytoplasmic feedback inhibitor of the UDP-GlcNAc 2-epimerase enzyme by binding to its allosteric site. The UDP-GlcNAc 2-epimerase kinase is the rate limiting step in sialic acid biosynthesis. If the enzyme does not work efficiently the organism cannot function correctly.
There are several ways in which ManNAc can be synthesised and three examples follow.
ManNAc is now manufactured in large quantities by New Zealand Pharmaceuticals Ltd, [4] in a commercial process from N-acetylglucosamine.
There is normally some level of glycan sialylation within a glycoprotein, but with the observation that incomplete sialylation can lead to reduced therapeutic activity, it becomes relevant to assess the cell-lines and culture media to “humanise” the glycoprotein to improve performance and yield and reduce manufacturing costs. [5] Keppler et al. [6] demonstrated that the GNE enzyme was rate limiting in human hematopoietic cell lines and affected efficiency in cell surface sialylation. The activity of the GNE enzyme is now recognised as one of the defining features in the efficient production of sialylated recombinant glycoprotein therapeutic drugs. [7] Improved sialylation after the addition of ManNAc and other supporting ingredients to the culture medium not only increases manufacturing yield, but also improves therapeutic efficacy by increasing solubility, increasing half-life and reducing immunogenicity by reducing the formation of antibodies [8] to the therapeutic glycoprotein. [9]
When the GNE epimerase kinase does not function correctly in the human body thereby reducing the available ManNAc, it is reasonable to assume that treatment with ManNAc could assist with improving health benefits. The therapeutic potential for ManNAc is currently being assessed in several diseases in which therapy could benefit from its ability to enhance the biosynthesis of sialic acid.
The disease GNE myopathy [formerly known as hereditary Inclusion Body Myopathy (HIBM), and Distal Myopathy with Rimmed Vacuoles (DMRV)] is manifested as progressive muscle weakness. GNE myopathy is a rare genetic disorder caused by hyposialylated muscle proteins and glycosphingolipids [10] because there is insufficient metabolic ManNAc to form the Neu5Ac terminal sugar. There is no available therapy [11] [12] to treat GNE myopathy.
There is a growing body of evidence that reduced activity of the GNE enzyme in the sialylation pathway in kidney tissue could contribute to several glomerular kidney diseases, [13] [14] due to the lack of the Neu5Ac terminal sugar on several kidney glycoproteins.
Three kidney diseases that affect both children and adults are minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS) and membranous nephropathy (MN). These diseases are characterized by proteinuria (protein in the urine) and in the case of FSGS, a tendency to progressive scarring of the glomerulus (the filtering units of the kidneys) that leads to end-stage kidney disease. Several therapies are available for these diseases, but these therapies do not provide lasting reduction in proteinuria for many subjects and there can be severe side-effects.
There is now substantial pre-clinical evident correlating with human kidney biopsy samples, that some patients with MCD, FSGS or MN have kidney sialic acid insufficiency on their glomerular proteins. ManNAc therapy may increase sialic acid production and subsequently increase sialylation of glomerular proteins. [15]
Sialic acids are a class of alpha-keto acid sugars with a nine-carbon backbone. The term "sialic acid" was first introduced by Swedish biochemist Gunnar Blix in 1952. The most common member of this group is N-acetylneuraminic acid found in animals and some prokaryotes.
Hereditary inclusion body myopathies (HIBM) are a group of rare genetic disorders which have different symptoms. Generally, they are neuromuscular disorders characterized by muscle weakness developing in young adults. Hereditary inclusion body myopathies comprise both autosomal recessive and autosomal dominant muscle disorders that have a variable expression (phenotype) in individuals, but all share similar structural features in the muscles.
Heparan sulfate (HS) is a linear polysaccharide found in all animal tissues. It occurs as a proteoglycan in which two or three HS chains are attached in close proximity to cell surface or extracellular matrix proteins. It is in this form that HS binds to a variety of protein ligands, including Wnt, and regulates a wide range of biological activities, including developmental processes, angiogenesis, blood coagulation, abolishing detachment activity by GrB, and tumour metastasis. HS has also been shown to serve as cellular receptor for a number of viruses, including the respiratory syncytial virus. One study suggests that cellular heparan sulfate has a role in SARS-CoV-2 Infection, particularly when the virus attaches with ACE2.
Tunicamycin is a mixture of homologous nucleoside antibiotics that inhibits the UDP-HexNAc: polyprenol-P HexNAc-1-P family of enzymes. In eukaryotes, this includes the enzyme GlcNAc phosphotransferase (GPT), which catalyzes the transfer of N-acetylglucosamine-1-phosphate from UDP-N-acetylglucosamine to dolichol phosphate in the first step of glycoprotein synthesis. Tunicamycin blocks N-linked glycosylation (N-glycans) and treatment of cultured human cells with tunicamycin causes cell cycle arrest in G1 phase. It is used as an experimental tool in biology, e.g. to induce unfolded protein response. Tunicamycin is produced by several bacteria, including Streptomyces clavuligerus and Streptomyces lysosuperificus.
The enzyme UDP-glucose 4-epimerase, also known as UDP-galactose 4-epimerase or GALE, is a homodimeric epimerase found in bacterial, fungal, plant, and mammalian cells. This enzyme performs the final step in the Leloir pathway of galactose metabolism, catalyzing the reversible conversion of UDP-galactose to UDP-glucose. GALE tightly binds nicotinamide adenine dinucleotide (NAD+), a co-factor required for catalytic activity.
In enzymology, an UDP-N-acetylglucosamine 2-epimerase is an enzyme that catalyzes the chemical reaction
Nucleotide sugars are the activated forms of monosaccharides. Nucleotide sugars act as glycosyl donors in glycosylation reactions. Those reactions are catalyzed by a group of enzymes called glycosyltransferases.
In enzymology, a N-acetylglucosaminylphosphatidylinositol deacetylase (EC 3.5.1.89) is an enzyme that catalyzes the chemical reaction
In enzymology, a glycoprotein-N-acetylgalactosamine 3-beta-galactosyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a N-acetyllactosaminide beta-1,3-N-acetylglucosaminyltransferase is an enzyme that catalyzes the chemical reaction
Bifunctional UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase is an enzyme that in humans is encoded by the GNE gene.
N-acylglucosamine 2-epimerase is an enzyme that in humans is encoded by the RENBP gene.
UDP-N-acetyl-2-amino-2-deoxyglucuronate dehydrogenase (EC 1.1.1.335, WlbA, WbpB) is an enzyme with systematic name UDP-N-acetyl-2-amino-2-deoxy-alpha-D-glucuronate:NAD+ 3-oxidoreductase. This enzyme catalyses the following chemical reaction:
UDP-2-acetamido-3-amino-2,3-dideoxy-glucuronate N-acetyltransferase is an enzyme with systematic name acetyl-CoA:UDP-2-acetamido-3-amino-2,3-dideoxy-alpha-D-glucuronate N-acetyltransferase. This enzyme catalyses the following chemical reaction
N-acetylneuraminylgalactosylglucosylceramide beta-1,4-N-acetylgalactosaminyltransferase (EC 2.4.1.165, is an enzyme that catalyses the following chemical reaction:
Alpha-1,6-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase is an enzyme with systematic name UDP-N-acetyl-D-glucosamine:2,6-bis(N-acetyl-beta-D-glucosaminyl)-alpha-D-mannosyl-glycoprotein 4-beta-N-acetyl-D-glucosaminyltransferase. This enzyme catalyses the following chemical reaction
N-acetyl-beta-glucosaminyl-glycoprotein 4-beta-N-acetylgalactosaminyltransferase is an enzyme with systematic name UDP-N-acetyl-D-galactosamine:N-acetyl-beta-D-glucosaminyl-group 4-beta-N-acetylgalactosaminyltransferase. This enzyme catalyses the following chemical reaction
Protein O-GlcNAc transferase also known as OGT or O-linked N-acetylglucosaminyltransferase is an enzyme that in humans is encoded by the OGT gene. OGT catalyzes the addition of the O-GlcNAc post-translational modification to proteins.
UDP-N-acetylglucosamine 2-epimerase (hydrolysing) (EC 3.2.1.183, UDP-N-acetylglucosamine 2-epimerase, GNE (gene), siaA (gene), neuC (gene)) is an enzyme with systematic name UDP-N-acetyl-alpha-D-glucosamine hydrolase (2-epimerising). This enzyme catalyses the following chemical reaction
UDP-2,3-diacetamido-2,3-dideoxyglucuronic acid 2-epimerase is an enzyme with systematic name 2,3-diacetamido-2,3-dideoxy-alpha-D-glucuronate 2-epimerase. This enzyme catalyses the following chemical reaction