  Structural transition induced by a local conformational change in
biomolecules is formulated based on the generalized Langevin theory for the
structural fluctuation of a molecule in solution, and the linear response
theory, derived by Kim and Hirata in 2012. A chemical/mechanical change
introduced at a moiety of biomolecules, such as an amino acid substitution or a
structural change of a chromophore by the photo-excitation, is considered as a
perturbation, and the rest of the protein as the reference system. The
linear-response equation consists of two parts: a mechanical/chemical
perturbation introduced at the moiety, and the variance-covariance matrix of
the reference system that works as a response function. The physical meaning of
the equation is transparent: the force exerted by atoms in the moiety induces
the displacement in an atom of protein, which propagates through the
variance-covariance matrix to cause a global conformational change in the
molecule. A few examples of possible application of the theory, including those
in industry, are suggested.
