Immunohistochemical localisation of D-beta-aspartic acid-containing proteins in climatic droplet keratopathy.
OBJECTIVE
Biologically uncommon D-beta-aspartic acid (D-beta-Asp) accumulates in the body with age and is involved in the ageing process. In the present study, the localisation of D-beta-Asp-containing proteins was investigated in surgical specimens with climatic droplet keratopathy (CDK), one of the ocular changes related to the ageing process.


METHODS
Immunohistochemical localisation of D-beta-Asp-containing proteins using polyclonal antibodies raised against D-beta-Asp-containing peptides was examined in three corneas with CDK, three corneas with interstitial keratitis, six corneas with bullous keratopathy, and three corneas without any corneal diseases.


RESULTS
Strong immunoreactivity to D-beta-Asp-containing peptide was detected in all the surgical specimens with CDK. In contrast, no immunoreactivities to D-beta-Asp-containing peptides were detected in the surgical specimens with bullous keratopathy, interstitial keratitis, or no corneal diseases.


CONCLUSIONS
CDK was regarded as aggregations of D-beta-Asp-containing proteins. The formation of D-amino acids in protein causes the different side chain orientations and beta-linkage of Asp residues elongates the main chain of proteins. Therefore, D-beta-Asp formation will result in a partial unfolding of proteins leading to the aggregation of proteins seen in CDK.
Kaji
Y
Y
Department of Ophthalmology, Tsukuba University Institute of Clinical Medicine, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8575, Japan. sanken-tky@umin.ac.jp
Oshika
T
T
Takazawa
Y
Y
Fukayama
M
M
Fujii
N
N
D000368:Aged; D003316:Corneal Diseases / Q000378:metabolism*; D026603:D-Aspartic Acid / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D026581:Isoaspartic Acid / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D014466:Ultraviolet Rays / Q000009:adverse effects
D026581:Isoaspartic Acid; D026603:D-Aspartic Acid