Properties of nano protein particle in solutions of myofibrillar protein extracted from giant squid (Dosidicusgigas)

Abstract

This work studied the quantitation of myofibrillar protein isolated from giant squid by three methods (Bradford, biuret, and direct ultraviolet absorbance). The results were examined in relation to compositional size exclusion chromatography, static light scattering, zeta-potential and thermal analysis; comparisons between the apparent vs. the true protein concentration revealed the existence of disk-like nano protein particles (NPP) with a height of 2-3 nm, diameters ranging from several tens nm to 140 nm, and fractal dimensions d_f of less than 1.3. In order to probe the heterogeneity of NPP particles, their properties were studied under consecutive dilutions: the d_f decreased from 1.265 to 1.087, the zeta-potential increased from -4.55 mV to -1.83 mV, the denaturation temperature reduced from 63.9 °C to 58.6 °C, and the endothermic enthalpy reduced from 0.529 J s^-1 to 0.362 J s^-1. In addition, ca. 90% protein molecules in solution were aggregated to form NPP.

Keywords: Myofibrillar protein; Nano protein particle (NPP); Solid phase.