Abstract:
In a previous study we reported that a compound having the structure 2 could be detected in digested human lenses using LS–MS/MS. We reported that the structure 2 could be formed by the combined action of glycolaldehyde and glyceraldehyde. Recently we found that structures 1 and 3 could be formed by the individual action of glycolaldehyde or glyceraldehyde on Boc–Lys in vitro. The purpose of this study was to find if structures 1 and 3 could be detected in digested human eye lenses.
Human lenses were subject of digestion using a set of proteolytic enzymes. 13C labeled standards of compounds 1 and 3 were added to the digest obtained. HPLC fractions containing the standards were collected. MS and MS/MS spectra of the fractions corresponding to the standards were recorded.
The MS and MS/MS spectra suggest that both the 13C labeled standards and the corresponding non–labeled products were present in the fractions collected. This is an evidence that structures 1 and 3 exist in human lens.
The presence of structures 1, 2 and 3 in lens proteins suggests that glycolaldehyde and glyceraldehyde are effective glycation agents in human eye lens according to the scheme given bellow.
Keywords: aging • cataract • protein modifications-post translational