THE STRUCTURE AND PROPERTIES OF NAPIN-SEED STORAGE PROTEIN FROM RAPE (BRASSICA-NAPUS L.)

Purification to homogeneity of 2S albumin storage protein from rape se eds (napin) was achieved and its secondary structure and conformationa l stability were characterised by circular dichroism (CU), and high-se nsitivity differential scanning calorimetry (HS-DSC), Deconvolution of the far-UV CD spectrum of napin revealed about 25% of alpha-helix and 38% of beta-sheet structure at neutral and slightly acid pH. HS-DSC d ata show a single peak of protein denaturation with maximum at 101 deg rees C and 88 degrees C at pH 6.0 and 3.0, respectively. This disclose s very high stability of napin tertiary structure. The thermal denatur ation of napin is irreversible due to secondary processes such as hydr ophobic aggregation of the unfolded protein. The deconvolution of the transition profile at pH 3.0 carried out with assumption that napin ag gregation does not contribute to the transition parameters allows to d istinguish two constituent transitions which may be attributed to two different domains in napin folding.