RAMAN SPECTROSCOPIC INVESTIGATION OF LENS AGING & CATARACT FORMATION

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The objective of this research is to investigate the cataract formation and aging of eye lens using Raman spectroscopy. It is has been proposed that oxidation of lens crystallins leading to disulfide cross linking and associated changes in protein conformation are moajor steps in lens aging anf cataract formation. We have obtained Raman spectra of native gamma II crystallin in monomer form and dimer form determined by HPLC, and control samples. Raman spectroscopy detected disulfide formation (S-S) at 511 cm-1. We followed the oxidation of crystallin protein by following the appearance of S-S frequency at 511 cm-1 and disappearance S-H frequency near 2500-2600 cm-1. The initial Raman results also suggested that disulfide formation or oxidation does not result in significant changes in secondary conformation of the protein. Currently we are trying determine whether the di-sulfide cross linking is intramolecular or inter molecular and estimate the ratio if it is due to both.