Figure 4. Model structure representation of wild (green) and Thr84Ala mutant (cyan) crystallin beta-A4 (CRYBA4) protein. A: The Thr84 hydroxyl group forms a hydrogen bond with the main chain carbonyl oxygen of Gly159 and the amide nitrogen of the Gln161 side chain. Asn83 is involved in the hydrogen-bonded interaction with the Gly159 main chain nitrogen atom and the Tyr157 main chain oxygen. B: The Ala84 mutant cannot be involved in this interaction. The important interacting residues are rendered as balls and sticks, and the hydrogen bonds are depicted as black dotted lines.