Analysis of normal human fetal eye lens crystallins by high‐performance liquid chromatography/mass spectrometry

High-performance liquid chromatography/mass spectrometry (HPLC/MS) was used to characterize the water-soluble and water-insoluble fractions of human fetal eye lens crystallins. This age group was selected since their crystallins are not expected to have accumulated significant amounts of either age- or cataract-related post-translational modifications owing to their young age. This analysis permitted the identification and determination of the extent of post-translational modifications for a range of crystallins in a single procedure. The excellent agreement between the calculated and experimental molecular weights from HPLC/MS implies that the published sequences for the crystallins αA2, αB2, βA3, βB2 and γC are correct. This agreement also demonstrates that these proteins do not contain any previously undetected post-translational modifications. In addition, the molecular weights for many crystallins with unknown sequences and/or post-translational modifications were determined to within several mass units. This appears to be the first reported analysis of the post-translational modifications occurring in crystallins from this age group. By providing the molecular weights of the native human crystallins, this study provides a baseline for future comparisons of the age- and cataract-related post-translational modifications of human lens crystallins.