Interactions between globular proteins and procyanidins of different degrees of polymerization

Isothermal titration calorimetry (25°C, pH 5.5) of α-lactalbumin titrated with procyanidins of various average degrees of polymerization ( n): epicatechin (×); procyanidin dimer (Δ); procyanidins of n=5.5 (○); procyanidins of n=7.4 (▴).

Isothermal titration calorimetry (25°C) of proteins titrated with procyanidins of an average degree of polymerization of 5.5 at different pH values for (a) α-lactalbumin and (b) lysozyme: pH 3.0 (); pH 5.5 (○); pH 7.5 (■).

Protein [0.5% (wt/vol)] solubility as a function of pH, in the absence or presence of 5mol of procyanidins per mol of protein: α-lactalbumin (■)), lysozyme (•), and BSA (▴) in the absence of procyanidins; α-lactalbumin (□), lysozyme (○), and BSA (▵) in the presence of procyanidins of an average degree of polymerization of 7.4.

Cumulative number of bubbles as a function of bubble diameter of foam from α-lactalbumin at pH 7.0, after 15 and 49min of foam formation, in the absence (—) or in the presence of procyanidins of various degrees of polymerization (): n=2.0 (…); n=5.0 (— … —); and n=7.4 (– –). (a) Two moles of procyanidin/protein; (b) five moles of procyanidin/protein.

Images of foam from α-lactalbumin in the absence (left) and in the presence (right) of 2mol of procyanidins (with an average degree of polymerization of 5.0) per mol of α-lactalbumin at pH 4.0 (after 49min of foam formation).

Cumulative number of bubbles as a function of bubble diameter, in the absence (—) or in the presence (– –) of 2mol of procyanidins (with an average degree of polymerization of 5.0) per mol of α-lactalbumin at pH 4.0 (after 15 and 49min of foam formation).