A method for determination of molecular weight of silk fibroin by non-gel sieving capillary electrophoresis

摘要

With the main advantages of convenient injection of sieving matrices, easy wash, reusable capillary and unattended operation, a simple non-gel sieving capillary electrophoresis (NGSCE) method was established to determine molecular weight (MW) of silk fibroin using capillary electrophoesis system (CE) combined with a variable wavelength UV-Vis diode array detector (DAD). The background electrolyte with a pH of 8.8 was based on the three components polyethylene glycol, tris(hydroxymethyl)aminomethane (Tris) and sodium dodecyl sulfate (SDS). Phosphate buffer (PBS) composed of NaCl, NaH2PO4 and Na2HPO4, and TS buffer made up of Tris and SDS were used to dissolve and dilute sample proteins. NGSCE results showed a good linear relationship with fine reproducibility between the migration time and the molecular weight of standard proteins. Based on electropherogram of NGSCE, it was found that the regenerated silk fibroin had a MW around 83 kDa with a wide molecular weight distribution (MWD). This absolute value is lower than the result obtained from the Lauryl sodium sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) due to their different principles, but their similar MWD shapes indicated that NGSCE could be a feasible, highly sensitive, rapid method for the determination of MW of silk fibroin.