Keratoconus: I. Biochemical studies.
The present study analyses collagenous and non-collagenous components from age-matched normal and keratoconus corneas. Intact keratoconus corneas showed decreased collagen, total protein, and hydroxylysine levels, with normal reducible collagen cross-linking. Non-collagenous fractions were isolated from corneas with a 4 M guanidine procedure. As demonstrated by PAGE-silver stain, the keratoconus cornea guanidine extracts had a 75 kDa band that was absent in normal cornea guanidine extracts. In addition, there was a markedly increased level of protein, uronic acid and neutral hexose in keratoconus extracts as compared with controls. Our Western blot studies showed increased affinity for the castor-bean agglutinin (RCA120, specific for terminal galactose) in the keratoconus extracts as compared with normals. These data suggest the presence of an abnormal noncollagenous component in keratoconus corneas.
Critchfield
J W
JW
Department of Nutrition, University of California, Davis 95616.
Calandra
A J
AJ
Nesburn
A B
AB
Kenney
M C
MC
D000328:Adult; D003094:Collagen / Q000378:metabolism; D003315:Cornea / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000378:metabolism; D006601:Hexoses / Q000378:metabolism; D006801:Humans; D006901:Hydroxylysine / Q000378:metabolism; D006909:Hydroxyproline / Q000378:metabolism; D007640:Keratoconus / Q000378:metabolism*; D037102:Lectins; D008875:Middle Aged; D014574:Uronic Acids / Q000378:metabolism
D005136:Eye Proteins; D006601:Hexoses; D037102:Lectins; D014574:Uronic Acids; D006901:Hydroxylysine; D003094:Collagen; D003545:Cysteine; D006909:Hydroxyproline