Molecular Simulation Study Based On Silk Fibroin

Silk fiber, with incomparable qualities other fibers don’t possess, has been favored formaking traditional clothing and works of art. However, the fact that it is vulnerable todegradation and aging poses a challenge for its wider application, thus studying the structure andproperties is necessary. The molecular simulation method vividly shows the behavior of theprotein molecules on the atomic scale, which would overcome technical limitation thatdiscourages the attainment of micro information and provide theoretical reference to micro fiberstructure and properties.In this paper, the molecular dynamics simulations for protein and peptide-based on thestructure and sequence of silk fibroin.was ran under the molecular dynamics software packageNAMD. The β-glucan recognition protein for an unfolding simulation results show that withincreasing temperature, the stability of β-sheet declines. The presence of water molecules wouldweaken the hydrogen bondage between the β-sheets and reduces its structural stability；Whenbuilding GAGAGA GAGAGA GAGAGA sequence peptide chains with different secondarystructure, the root mean square deviation in10ns simulation followed by β-parallel-sheetstructure> β-anti-parallel-sheet structure>-helix structure; Mutant GAGAGA GAGAGXGAGAGA twelfth residues, the simulation shows that the root mean square deviation of residuesdecreases following such order as glycine> alanine> valine> aspartate> tryptophan> serine>glutamate> tyrosine.This article established the electrochemical determination of tyrosine, and tested thephysical and chemical properties on silk aging at the same time。The electrochemical test resultsshow：Cyclic voltammetry can determinate tyrosine between0.1mmol/L~0.5mmol/L range，and without interference from the other amino acids. Physical and chemical testing analysis ofsilk hydrolyzed aging show：Water molecules attacking hydrogen bonds between the β-sheetcaused a decline in silk breaking strength, crystallinity, first increased and then decreased, therelative content of β-sheet and-helix secondary structure fell with the random structure risedduring the aging process. Physical and chemical testing analysis of silk UV aging show：UnderUV irradiation，the tyrosine in the silk fiber surface dehydrogenation cleaves to form a colorlysates caused the silk breaking strength, whiteness decreased,crystallinity decreased,tyrosinecontent decreased, β-sheet and-helix secondary structure relative content decreased with random structure rise.Molecular simulation can calculate about the nature of the structure by means of silk fibroin,silk fibers can study the mechanism of aging and the aging of the law provide some theoreticalreference, but also for the development of silk fibroin applications provide some research ideasand direction.