This is a proposal to document the nature of photochemical changes in lens crystallin proteins in solution. In the living lens, there are several potential mechanisms of UV damage, including: Direct crystallin photolysis, DNA photolysis, and damage to lens cell metabolism. Our experiments are designed to study crystallin photolysis separately. The hypothesis is that molecular changes in the crystallins, caused by UV radiation, can trigger a series of events, which finally lead to protein aggregation and insolubilization in solution, and to lens opacity in vivo. Molecular effects of UV radiation which we will study include: Crystallin crosslinking, protein conformational changes, and losses of specific amino acids in the peptide chains. Solution opacification is used as a marker of altered intermolecular interactions which lead to protein aggregation. The proposed experiments use UV wavelengths and doses which are comparable to those present in the human ambient environment. UV photodamage to human skin and eyes is presently of particular interest because of the reported trend toward decreased ozone-layer protection in the earth's atmosphere and recent epidemiological studies which indicate a positive correlation between UV exposure and human cataracts.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY006800-07
Application #
2160968
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1987-05-01
Project End
1997-04-30
Budget Start
1995-05-01
Budget End
1996-04-30
Support Year
7
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Georgia Institute of Technology
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
097394084
City
Atlanta
State
GA
Country
United States
Zip Code
30332
Hott, J L; Borkman, R F (1993) Concentration dependence of transmission losses in UV-laser irradiated bovine alpha-, beta H-, beta L- and gamma-crystallin solutions. Photochem Photobiol 57:312-7
Borkman, R F; Douhal, A; Yoshihara, K (1993) Picosecond fluorescence decay of lens protein gamma-II crystallin. Biophys Chem 47:203-11
Borkman, R F; Douhal, A; Yoshihara, K (1993) Picosecond fluorescence decay in photolyzed lens protein alpha-crystallin. Biochemistry 32:4787-92
Hott, J L; Borkman, R F (1992) Analysis of photo-oxidized amino acids in tryptic peptides of calf lens gamma-II crystallin. Photochem Photobiol 56:257-63
Li, D Y; Borkman, R F (1990) Photodamage to calf lenses in vitro by excimer laser radiation at 308, 337, and 350 nm. Invest Ophthalmol Vis Sci 31:2180-4
Tallmadge, D H; Borkman, R F (1990) The rates of photolysis of the four individual tryptophan residues in UV exposed calf gamma-II crystallin. Photochem Photobiol 51:363-8
Li, D Y; Borkman, R F; Wang, R H et al. (1990) Mechanisms of photochemically produced turbidity in lens protein solutions. Exp Eye Res 51:663-9
Dillon, J; Roy, D; Spector, A et al. (1989) UV laser photodamage to whole lenses. Exp Eye Res 49:959-66
Berger, J W; Vanderkooi, J M; Tallmadge, D H et al. (1989) Phosphorescence measurements of calf gamma-II, III, and IV crystallins at 77 and 293 K. Exp Eye Res 48:627-39
Hott, J L; Borkman, R F (1989) The non-fluorescence of 4-fluorotryptophan. Biochem J 264:297-9

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