Molecular masses of gamma-crystallins.

Bovine gamma-crystallins were isolated and analysed by electrospray mass spectrometry (ESMS). The mass of gamma II-crystallin was as predicted from the amino acid sequence and the mass of gamma IIIb-crystallin was close, but the mass of gamma IVa-crystallin was 59 Da greater than that expected. gamma IVa-Crystallin was digested with cyanogen bromide and the fragments were isolated before analysis by ESMS. The masses of the fragments did not correspond to the published sequence. The published sequence of gamma IVa-crystallin, which has been used to predict its three-dimensional structure, is incorrect.