Proteoglycans contain a 4.6 A repeat in muscular dystrophy corneas: x-ray diffraction evidence

Synchrotron x-ray diffraction patterns from macular corneal dystrophy (MCD) corneas contain an unusual reflection that arises because of an undefined ultrastructure with a periodic repeat in the region of 4.6 A. In this study, we compared with wide-angle x-ray diffraction patterns obtained from four...

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Bibliographic Details
Published in:Biophysical journal 1996-04, Vol.70 (4), p.1966-1972
Main Authors: Quantock, A.J., Klintworth, G.K., Schanzlin, D.J., Capel, M.S., Lenz, M.E., Thonar, E.J.
Format: Article
Language:English
Subjects:
Adult
Aged
Amidohydrolases - pharmacology
Biophysical Phenomena
Biophysics
Chondroitin Lyases - pharmacology
Collagen - analysis
Cornea - chemistry
Cornea - drug effects
Corneal Dystrophies, Hereditary - metabolism
Female
Glycosaminoglycans - analysis
Humans
Keratan Sulfate - analysis
Macromolecular Substances
Male
Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase
Proteoglycans - chemistry
X-Ray Diffraction
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Summary:Synchrotron x-ray diffraction patterns from macular corneal dystrophy (MCD) corneas contain an unusual reflection that arises because of an undefined ultrastructure with a periodic repeat in the region of 4.6 A. In this study, we compared with wide-angle x-ray diffraction patterns obtained from four normal human corneas and four MCD corneas. Moreover, portions of two of the MCD corneas were pretreated with a specific glycosidase to shed light on the origin of the 4.6 A reflection. None of the normal corneas produced an x-ray reflection in the region of 4.6 A, whereas all four of the MCD corneas did (MCD type I at 4.65 A and 4.63 A, MCD type II at 4.63 A and 4.67 A). This reflection was diminished after incubation of the MCD tissues with either chondroitinase ABC or N-glycanase. The findings indicate that glycosaminoglycans or proteoglycans contribute to the unusual MCD x-ray reflection and hence most likely contain a periodic 4.6 A ultrastructure. Furthermore, the results imply that periodic 4.6 A MCD ultrastructures reside in either intact, unsulfated lumican molecules and regions of the CS/DS-containing molecules or in a region of a hybrid macromolecular aggregate formed by the interaction of the two molecules.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(96)79761-8