keratan sulfate catabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the breakdown of keratan sulfate, a glycosaminoglycan with repeat units consisting of beta-1,4-linked D-galactopyranosyl-beta-(1,4)-N-acetyl-D-glucosamine 6-sulfate and with variable amounts of fucose, sialic acid and mannose units; keratan sulfate chains are covalently linked by a glycosidic attachment through the trisaccharide galactosyl-galactosyl-xylose to peptidyl-threonine or serine residues. [GOC:go_curators]

Keratan sulfate catabolism is a complex biological process involving the breakdown of keratan sulfate (KS), a glycosaminoglycan found primarily in cartilage, cornea, and bone. KS is composed of repeating disaccharide units of N-acetylglucosamine and galactose, with varying sulfation patterns. Its catabolism is essential for maintaining tissue homeostasis and preventing the accumulation of potentially harmful breakdown products.

The process begins with the enzymatic degradation of KS chains by a family of enzymes known as keratan sulfatases. These enzymes specifically cleave the sulfate groups from KS, releasing free sulfates and producing desulfated KS.

Following desulfation, the modified KS undergoes further degradation by a series of glycosidases. These enzymes hydrolyze the glycosidic bonds between the sugar residues in the KS chain, generating smaller oligosaccharides and monosaccharides.

Specific glycosidases involved in this process include:

* β-N-acetylhexosaminidase: cleaves the linkage between N-acetylglucosamine and galactose.
* β-galactosidase: hydrolyzes the β-1,4-glycosidic bond between galactose residues.

The breakdown products of KS, including desulfated KS, oligosaccharides, and monosaccharides, can be further processed or excreted from the body.

The precise regulation of keratan sulfate catabolism is crucial for maintaining tissue integrity. Dysregulation of this process can contribute to various diseases, including:

* **Osteoarthritis:** Increased KS catabolism in cartilage can lead to joint degeneration.
* **Corneal dystrophies:** Abnormalities in KS metabolism can cause corneal clouding and vision impairment.
* **Cancer:** Altered KS catabolism has been implicated in tumor growth and metastasis.

In conclusion, keratan sulfate catabolism is a tightly regulated process involving enzymatic degradation of KS chains by sulfatases and glycosidases. This process is essential for maintaining tissue homeostasis and preventing the accumulation of breakdown products. Dysregulation of KS catabolism can contribute to various diseases, highlighting the importance of understanding this complex biological pathway.'
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Proteins (2)

Compounds (5)