Abstract
Molecular conformation and crystal structure of poly-O-benzyl-L-serine (POBLS) and poly-L-serine (PLS) as model compounds related to silk sericin were investigated by means of an infrared spectrometer, an x-ray diffractometer, a differential scanning calorimeter and a polarized scope. A cross β molecular conformation was found in both POBLS and PLS. Crystals were presumed to be made up by stacking of, β-sheets, which were formed by cross β molecular chains. Since the side chains were interposed by the sheets, hydrogen bonds were formed between the side chains or between the side chain and the main chain. A needle-like crystal was observed in POBLS. In contrast, a spherulite was found in PLS. However, the molecular alignment in both crystals was similar, i.e. polypeptide chains were folded perpendicular to the direction of crystal growth, while the side chains oriented paralled to it.
