Enzymatic digestion and antioxidant activity of the native and molten globule states of camel [alpha]-lactalbumin: possible significance for use in infant formula
Résumé
Native- and molten globule states of [alpha]-lactalbumin ([alpha]-La) from camel and bovine milk were used for comparative assessment of digestibility and antioxidant activity. The proteolysis assessments were performed in the presence of gastrointestinal enzymes, using the o-phthaldialdehyde assay, and the antioxidant activity was carried out using a 2, 20-azinobis(3-ethylenebenzothiazoline-6-sulfonic acid based method. Camel and bovine [alpha]-La revealed similar sensitivity to proteolysis by pepsin. The degree of hydrolysis (DH) of camel [alpha]-La by either trypsin or chymotrypsin was noticeably higher than that of the bovine protein counterpart. This can be explained by the different conformational and structural features of these proteins, as shown by studies of intrinsic- and 8-anilinonaphthalene-1-sulfonic acid fluorescence. The greater antioxidant activity of camel [alpha]-La could be explained by the higher content of antioxidant amino-acid residues and different conformational features between bovine and camel [alpha]-La. The results may suggest that [alpha]-La produced from camel milk may be used for infant formulae as an alternative to that produced from bovine milk.