Molecular modelling of conformational changes in solvated αs1-casein peptides

• Published in: International dairy journal 1999-03, Vol.9 (3), p.207-213
• Main Authors: Malin, Edyth L., Brown, Eleanor M.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Food industries; Fundamental and applied biological sciences. Psychology; Milk and cheese industries. Ice creams; Molecular modelling; Peptides; αs1-Casein
• ISSN: 0958-6946; 1879-0143
• DOI: 10.1016/S0958-6946(99)00062-X

Computer models of α s1-casein peptides were simulated in an aqueous environment to compare their conformations as separate peptides with structural features of corresponding regions in the intact α s1-casein molecular model. Peptide sequences selected for investigation were based on sites of potential cleavage by chymosin and/or plasmin. Four large peptides and several smaller peptide fragments were refined by applying a series of molecular dynamics simulations and energy minimizations. Most peptides adopted conformations that were more compact than the conformations of the corresponding sequences in the intact α s1-casein model. The results indicated that sequences in the peptides that promote the open, flexible structure of the parent protein are likely to resist formation of new secondary structure during refinement. However, these regions can develop more local flexibility and additional turns because of the high proline content of α s1-casein. The region in which seven of the eight phosphoserine residues are located maintained its conformation throughout the refinement, but this region adopted a new conformation when phosphoserines were replaced with serines. The results demonstrate the potential for folding in casein peptides and highlight the features that promote the open, extended structures of the caseins.