Analysis of the effects of pH and salt on the conformation of the sericin particles by DLS and TEM measurements

• Published in: Guang pu xue yu guang pu fen xi Vol. 30; no. 5; p. 1391
• Main Authors: Wu, Li-Ping, Leng, Xiao-Jing, Sun, Yan, Ren, Fa-Zheng, Nakai, Shuryo
• Format: Journal Article
• Language: Chinese
• Published: China 01.05.2010
• Subjects: Animals; Bombyx; Hydrogen Bonding; Hydrogen-Ion Concentration; Microscopy, Electron, Transmission; Molecular Conformation; Salts; Sericins - chemistry; Spectroscopy, Fourier Transform Infrared; Static Electricity
• ISSN: 1000-0593
• DOI: 10.3964/j.issn.1000-0593(2010)05-1391-05

The particles conformation of the sericin protein extracted from silkworm Bombyx mori was studied under the conditions of different pH and salt concentrations by infrared spectroscopy (IR), dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements. The IR spectrum of sericin protein arises predominantly from C=O stretching vibration around the amide I region of 1 700-1 600 cm(-1). A strong trend of aggregation of the protein could be observed under specified experimental conditions. The apparent isoelectric point of the sericin protein was about 3.7. The DLS method was used to investigate the effects of pH and NaCl on the size distribution, where a large polydispersity of the system could be observed. Compared to pH 4 or high NaCl concentration, at pH 3, 8 or low NaCl concentration the sericin aggregation shows a relatively smaller size but larger polydispersity. TEM was used to investigate the microstructure of the aggregated sericin protein, where a loose and pine-like branched