Except for hyaluronic acid, the glycosaminoglycans are linked to proteins, usually attached covalently to serine or
threonine residues, and are hence also referred to as proteoglycans. Keratan sulfate I is attached to asparagine. The
synthesis of all glycosaminoglycans is dependent upon the presence of glucosamine-6-phosphate.
Glucosamine-6-phosphate
The body normally synthesizes glucosamine-6-phosphate by the transfer of an amino group from the amide of
glutamine to fructose 6-phosphate. Glucosamine can then be N-acetylated by an acetyltransferase enzyme to yield N-
acetyl glucosamine-6-phosphate and N-acetyl galactosamine, which are then linked to UDP. Both N-acetyl
glucosamine and N-acetyl galactosamine are used as monosaccharides to form various glycosaminoglycans. The
glycosaminoglycans in joint cartilage are comprised of repeating units of glucuronic acid and N-acetyl galactosamine. It
appears that as some people age, they lose the ability to manufacture suf icient levels of glucosamine-6-phosphate,
and thus, there is a reduction in the synthesis of N-acetyl galactosamine and N-acetyl glucosamine. The result is that
cartilage loses its ability to act as a shock absorber and erosion of cartilage and ground substance can lead to
osteoarthritis. Radioisotope studies using C14 glucosamine indicate that glucosamine supplementation is a good
substrate for a kinase enzyme which yields glucosamine-6-phosphate, which can then be used to form
glycosaminoglycans.
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Meschino Health Comprehensive Guide to Accessory Nutrients and Essential Oils
Accessory Nutrients and Essential Oils
The best form of glucosamine has been shown to be Glucosamine Sulfate. N-acetylglucosamine is a poor substrate
for a kinase activity and glucosamine hydrochloride has poor supportive evidence for its use. It appears that the sulfur
component of Glucosamine Sulfate may be critical to its beneficial effects on arthritis and other problems.
Glucosamine ingestion also has a concurrent effect on increasing collagen production by chondrocytes, helping to
reverse the osteoarthritic process.1-9
Clinical Conditions and Mechanisms