Pn. Bishop et al., EXTRACTION AND CHARACTERIZATION OF THE TISSUE FORMS OF COLLAGEN TYPE-II AND TYPE-IX FROM BOVINE VITREOUS, Biochemical journal, 299, 1994, pp. 497-505
We report for the first time that, after centrifugation of adult bovin
e vitreous, the hyaluronan-rich supernatant contains collagens which c
an be isolated in their intact forms by precipitation with 4.5 M NaCl.
This precipitate constituted approx. 4% of the total vitreous collage
n and comprised collagen types IX and II (in the approximate ratio of
4:1) with negligible amounts of type-V/XI collagen. Type-II collagen w
as present partly in a pro-alpha 1(II) form, suggesting that there is
active synthesis of type-II collagen into the matrix of adult bovine v
itreous. Type-IX collagen was purified (2-2.5 mg/l of vitreous) and it
s glycosaminoglycan chain composition was analysed. Bovine vitreous ty
pe-IX collagen always possessed a glycosaminoglycan chain of comparati
vely low M(r) that was predominantly 4-sulphated, with chondroitin 6-s
ulphate representing a more minor component. By contrast, chick vitreo
us has been shown to contain type-IX collagen which always possesses a
high-M(r) chondroitin sulphate chain that is predominantly 6-sulphate
d. The functional significance of these different glycosaminoglycan ch
ain lengths and sulphation patterns is discussed.