AFM and NMR imaging of squid tropomyosin Tod p1 subjected to high hydrostatic pressure: evidence for relationships among topography, characteristic domain and allergenicity

Abstract

The surface topography, characteristic domain and allergenicity of squid tropomyosin Tod p1 (TMTp1) treated under single- and two-cycle high hydrostatic pressure (HHP) were analyzed. Atomic force microscopy (AFM) showed that the HHP treatment led to the formation of a rougher surface of squid TMTp1; the two-cycle 600 MPa HHP treatment produced the largest effect, with a mean roughness, maximum height, skewness and kurtosis of 6.56 nm, 94.83 nm, 3.05 and 23.13, respectively. The HHP treatment caused lower IgE and IgG-binding capacities, indicating a significant reduction of the allergenicity (p < 0.05) due to variations in the AFM surface topography. The peaks of the main allergenic characteristics affected were 0.99, 1.16, 1.21, 1.79, 1.82, 2.84, 2.88 and 3.37 ppm (in the initial ¹H nuclear magnetic resonance (NMR) spectra). The HHP treatment changed the AFM surface topography and caused the migration or disappearance of the related ¹H NMR peaks; these changes were significantly correlated (p < 0.05) with the reductions in allergenicity observed.