We have investigated the dynamics of a protomer coupled to two different decoherent environments, each in a configuration called the spin star configuration. Using the quantum mechanics method, in different situations, we obtain the analytical expressions for the transition probability in the protomer system. In thermal equilibrium, there exist well-defined ranges of parameters for which decoherent interaction between the protomer and the environment assists energy transfer in the protomer system, while in pure quantum mechanics states, the decoherent interaction assists energy transfer for an eigenstate but against energy transfer for quantum mechanics averages. In particular, we also find that the dimerization of two bacteriochlorophylls in protomer can always assist energy transfer in certain parameter range, and in the appropriate spin bath energy, the efficiency of energy transport is sensitively depended on the temperature of environments.
