Changes in the secondary structure and aggregation of concanavalin A (Con A) were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The secondary structure of Con A has been shown to be affected by factors such as temperature, pH, ionic strength, pressure and the presence of sugars. DSC studies indicated that the thermal stability of Con A is enhanced in the presence of salts, sugars and by pH. Detailed examination of the conformation-sensitive amide I band in the FTIR spectrum of Con A revealed that concentration, sugars, metal ions and pressure (range from 0-14.4 kbar) had no effect on the structural conformation of Con A at room temperature. Variable-temperature FTIR studies of the thermal stability of Con A as a function of pH showed that maximum thermal stability is achieved under alkaline conditions (pH 8-10). It was also found that sugars enhanced the thermal stability of Con A to varying degrees and that the stabilizing effect of the sugar was not dependent on the sugar binding specificity of the lectin.

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