Compact residual structure in lentil lectin at pH 2

Lentil lectin obtained from Lens culinaris collected in the La Armuna area (Salamanca, Spain) was examined by high-sensitivity differential scanning c alorimetry, fluorimetry and measurements of circular dichroism at pH 2.0 an d 7.4. At pH 2.0 the lentil lectin is not in the native state; however, at this pH it does show signs of a residual structure that breaks down upon he ating. The lentil lectin at pH 2 shares some similarities with what has bec ome known as the molten globule state. The thermal denaturation of intact ( pH 7.4) and partially unfolded (pH 2.0) lentil lectin was irreversible and strongly dependent upon the scan rate, suggesting that its denaturation is under kinetic control. The process of lentil lectin denaturation is interpr eted in terms of the simple kinetic model, N-k --> D, where k is a first-or der kinetic constant that changes with temperature, as given by the Arrheni us equation; N is the native state, and D is the denatured state.