title: Refining hot-water extracted silk sericin by ethanol-induced precipitation.
abstract: In order to improve some inherent disadvantages in the mechanical properties of silk sericin (SS), we prepared ethanol-precipitated sericin (EpSS) by adding ethanol into hot-water extracted sericin (HS) solution. EpSS had higher viscosity compared to HS and it was due to the differences in their molecular weight distribution (MWD). The different MWD of EpSS was due to the different solubility of sericin molecules at various concentrations of ethanol, and the amino acid composition of EpSS showed that the more hydrophobic sericin is precipitated more readily in the presence of ethanol. The secondary structure of sericin is also changed from a random coil to β-sheet structure when the amount of ethanol added is high enough. The DSC analysis also revealed that EpSSs has a more compact structure. Finally, when beads were prepared from EpSS, they had enhanced compressive strength compared to those from HS.
authors.affiliation: Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Hanjin
authors.initials: H
authors.lastname: Oh
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Moo Kon
authors.initials: MK
authors.lastname: Kim
authors.forename: In Chul
authors.initials: IC
authors.lastname: Um
authors.forename: Ki Hoon
authors.initials: KH
authors.lastname: Lee
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001696:Biomechanical Phenomena; D012831:Bombyx / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D011232:Chemical Precipitation; D002942:Circular Dichroism; D019245:Compressive Strength; D000431:Ethanol / Q000737:chemistry*; D006358:Hot Temperature; D057927:Hydrophobic and Hydrophilic Interactions; D008970:Molecular Weight; D017433:Protein Structure, Secondary; D047030:Sericins / Q000737:chemistry / Q000302:isolation & purification*; D012997:Solvents / Q000737:chemistry; D014783:Viscosity; D014867:Water / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D047030:Sericins; D012997:Solvents; D014867:Water; D000431:Ethanol