Proteolysis cartilage

Conversely, the connective tissues and cartilage are much more resistant to proteolysis and will survive for a longer period of time, although they too will eventually succumb to the effects of putrefaction. Reticulin, epidermis, and muscle protein will resist breakdown for some time, whereas collagen and keratin may survive for longer periods (Linch and Prahlow 2001). Keratin is an insoluble fibrous protein found in the skin, hair, and nails, and its resistance to attack by most proteolytic enzymes (Gupta and Ramnani 2006) is the reason it is often found intact amongst skeletal remains, particularly in burial environments (Macko et al. 1999). 

Rabbit synovial fibroblasts in culture have been shown to secrete a metal dependent neutral proteinase that degrades the protein core of cartilage proteoglycans. The enzyme is found in a latent form in the culture medium and is activated by limited proteolysis.23... 

Heathfield TF, Onnerfjord P, Dahlberg L, Heinegard D. Cleavage of fibromodulin in cartilage explants involves removal of the N-terminal tyrosine sulfate-rich region by proteolysis at a site that is sensitive to matrix metalloproteinase-13. J Biol Chem 2004 279 6286-6295. 

Fig. 3.5 Schematic structure of aggrecan and the sugar components in it. The blue horizontal line in the middle represents the protein eomponents from the A/-terminus to the C-terminus. Aggrecan is sensitive to break-up (proteolysis) where the dotted arrow indicate, this is responsible for the degradation of cartilage tissue. (Authors own work and http //glycoforum.gr.jp/science/word/pro-teoglycan/PGAOOE.html, permission obtained from copyright-owner)...

Glycosaminoglycans, solubilized from articular cartilage and synovial fluid by proteolysis, have been separated by electrophoresis, allowing microgram quantities of individual polysaccharides to be detected. i e electrophoretic separation of glycosaminoglycans in cationic media may not represent a normal electrophoresis but has more in common with phenomena that are associated with electrofocusing techniques. Caution in interpreting data from this and similar electrophoretic techniques has ben advocated. ... 

Structural similarities in two major link-proteins from bovine nasal cartilage have been identified after proteolysis and examination of their peptide patterns. The major difference between them is in their carbohydrate contents. 

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