Characterization and Structural Identification of an 11S Globulin of Juglans mandshurica Maxim. Kernel from the Changbai Mountains in China

Abstract

ABSTRACT:The major seed storage protein 11S globulin from Juglans mandshurica Maxim. (JSG) was isolated and purified to identify its structure and analyze its physicochemical properties. JSG was found to be composed of two distinct major polypeptides with molecular masses of ~23 and ~20 kDa, and whose amino acid sequences are highly similar to those of the 11S globulin from J. regia in the NCBI database. JSG contains essential amino acids that correspond to the adult standard recommended by FAO/WTO. Differential scanning calorimetry revealed a single endothermic peak with a denaturation temperature of 96.83 °C and an enthalpy value of 12.07 J/g. The secondary structure of the JSG consists of β-sheets (32.83%) and α-helices (11.67%). A red shift was also observed in the fluorescence spectra with guanidine hydrochloride (GdnHCl) or urea as denaturant; GdnHCl was proven to be a stronger denaturant than urea.