to deduce that H-fibroin Cys-c1 and Cys-c4 forms an intramolecular disulfide bond, while <b>Cys-c20 forms an intermolecular disulfide linkage with Cys-172
<figcaptionclass="figure-caption">Chromatography of the L-fibroin fractions and peptide sequence analysis, identifying the specific fractions containing