Lubrisiinia hajoittavat entsyymit

LÄHDE:  Thesis  Liaqat Ali. Bio.Lubrication. Strutural investigation of Lubricin and its glykosylation.
Sitaatteja joita löydän  väitöskirjasta:'

In vitro; in vivo:

"Lubricin has been found to be extensively degraded by papain, trypsin and pronase and to  a lesser extent by pepsin. (Flannery et al. 1999).
Other proteases such as neutrophil elastase ( a serine protease) and cathepsin B ( a cysteine protease) are also able to degrade lubricin in vitro (Jones et al. 2003; Elsaid et al. 2005)

Interestingly lubricin tryptic peptides were detected as low as the 30 - 65 kDa region. These fragments are unlikely to contain the full  mucin like domain,  but more likely an N- or C-terminal domain with a portion of mucin-like domain( non-glycosylated N-terminus has a mass of 33,8 kDa and the C-terminus 35,4 kDa)

So far it is not clear whether they were from unique cleavages along lubricin sequence or just randomly excised in vivo 

Evidence has indicated N-terminus of lubricin is more sensitive to neutrophil elastase (Elsaid et al. 2005).
Purified neutrophil elastase has been shown to damage cartilage explants in vitro (Burkhardt et al.  1988)
Also neutrophil elastase, and not MMPs, can destroy the superficial layer of cartilage where lubricin locates.
Consequently, MMPs have better access to cartilage molecules in less superficial layers of cartilage (Jasin et Taurog 1991).p. 145. Paper II.


"In cartilage, MMPs are  the principal proteases capable of degrading a wide variety of the extracellular matrix components (Nagase et  Woessner 1999=)
The released fragments of lubricin together with other synovial residual proteins and cartilage matrices floating in synovial fluid /SF)  may be detected by biochemical or immunochemical assaey. The profile of the protein fragments within synovial fluid may represent diagnostic pr prognostic biomarker for the degenerative  diseases." p. 133 Paper II.


"Proteins identified in enriched synovial fluid sample:
Fibronectin
Basement specific membrane specific heparan sulfate proteoglycan core protein
Apolipoprotein B-100
Lubricin
Alpha-2-macroglobulin
Aggrecan core protein
Serum albumin (HSA)"
P. 141, Paper II.