Analysis of the nonlinear behavior of ascaris trypsin inhibitor from NMR data

The characteristics of attractor control of the conformational changes of the trypsin inhibitor induced by pH variation have been detected. The autocorrelation functions for the changes in the root-mean-square fluctuations of the atoms caused by the pH variation show the damping expected for the control of an attractor, the Poincaré plot presents a region that is preferentially occupied and the first Lyapunov coefficient is positive, λ=0.094±0.001. The power spectrum is broad and the linear fit of power spectrum represented in a log–log scale shows broadband profile with 1/f-like distributions that are typical for chaotic processes. The saturation of the integral correlation coefficient with increasing number of coordinates in the phase space indicates the presence of an attractor with the dimension 2.24±0.15.