  The cosmological model with an interaction between dynamical quintessence
dark energy and cold dark matter is considered. Evolution of a dark energy
equation of state parameter is defined by a dark energy adiabatic sound speed
and a dark sector interaction parameter, which must be more physically correct
model then a previously used in which such evolution was given by some fixed
dependence on scale factor. The constraints on interaction parameter and other
parameters of the model was obtained using a cosmic microwave background,
baryon acoustic oscillations and supernova SN Ia data.
