Besides collagen, elastin is the most common connective tissue structural protein in
vertebrates and similar to collagen relatively resistant to non-specific degradation.
Typical elastolytic proteases are the serine-dependent pancreatic and leukocyte elastases,
the Zn-dependent matrix metalloproteinase 12, and several lysosomal cysteine proteases.
Among the cysteine cathepsins, cathepsins S, K and V are highly potent elastases with
cathepsin V displaying the highest activity among all known mammalian elastases.
Despite a shared amino acid sequence identity of over 80% between cathepsins V and L
and very similar subsite specificities, only cathepsin V has a potent elastase activity
whereas cathepsin L lacks it. A series of chimera mutants containing various proportions
of cathepsin V and cathepsin L were constructed in an attempt to define a specific region
needed for elastin degradation. It was found that retaining the peptide sequence region
from amino acids 89 to 119 of cathepsin V preserves the mutant’s elastolytic activity
against elastin-Rhodamine conjugates whereas the region FTVVAPGK (amino acids
112-119) contributes approximately 60% of activity retention. Several additional mutant
proteins involving mutual swapping of residues VDIPK (amino acids 113-117) of
cathepsin L with residues TVVAPGK (amino acids 113-119) of cathepsin V, deletion of
Glyl 18 from cathepsin V, and insertion of Gly between Prol 16 and Lysi 17 in cathepsin
L were constructed and evaluated for their elastolytic activities. The results obtained with
those mutant cathepsin proteins support the importance of the amino acid region spanning
the residues from 112 to 119 in cathepsin V. Based on the 3-D structure of cathepsin V,
this peptide region is located below subsite binding pocket S2 and forms a wall-like
barrier which may act as an exosite for the productive binding of cross-linked elastin.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU./4069 |
| Date | 11 1900 |
| Creators | Chen, Li Hsuen |
| Publisher | University of British Columbia |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | 1743703 bytes, application/pdf |
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