PURIFICATION AND CHARACTERIZATION OF THE PHYSICOCHEMICAL PROPERTIES OF THE ALBUMIN FRACTION FROM THE SEEDS OF AMARANTHUS-HYPOCHONDRIACUS

The major albumin fraction (i.e. albumin-1) of Amaranthus hypochondriacus was isolated and purified to homogeneity, employing a protein solubilization step followed by gel filtration chromatography. The albumin was found to possess a molecular mass of 133400 Da and to be composed of a number of homogeneous low molecular weight subunits, thereby classifying the albumin as a homo-oligomer. The subunits were found to be held together by secondary forces (e.g. hydrogen bond, hydrophobic interactions) with no evidence of any covalent disulfide linkages. Physicochemical tests on the charge profile of the oligomer using electrophoretic isoelectric focusing, electrophoretic titration and zeta potential analysis indicated a pI of 7.50, below which the oligomer was substantially positively charged. Secondary structure analysis revealed that the albumin possessed relatively high levels of beta-sheet but very little discernable tertiary structure, as evidenced by relatively low near-UV (i.e. 240-320 nm) circular dichroic band intensities.