On the roles of the alanine and serine in the β-sheet structure of fibroin.
In its silk II form, fibroin is almost exclusively formed from layers of β-sheets, rich in glycine, alanine and serine. Reported here are computational results on fibroin models at semi-empirical, DFT levels of theory and molecular dynamics (MD) for (Gly)10, (Gly-Ala)5 and (Gly-Ser)5 decapeptides. While alanine and serine introduce steric repulsions, the alanine side-chain adds to the rigidity of the sheet, allowing it to maintain a properly pleated structure even in a single β-sheet, and thus avoiding two alternative conformations which would interfere with the formation of the multi-layer pleated-sheet structure. The role of the serine is proposed to involve modulation of the hydrophobicity in order to construct the supramolecular assembly as opposed to random precipitation due to hydrophobicity.
['Carrascoza Mayen|Juan Francisco|JF|', 'Lupan|Alexandru|A|', 'Cosar|Ciprian|C|', 'Kun|Attila-Zsolt|AZ|', 'Silaghi-Dumitrescu|Radu|R|']
D000409:Alanine D000595:Amino Acid Sequence D004151:Dipeptides D005349:Fibroins D008958:Models, Molecular D056004:Molecular Dynamics Simulation D017433:Protein Structure, Secondary D012694:Serine
β-sheet Fibroin Silk II DFT Molecular modeling Semiempirical