In recent years, single-molecule experiments have emerged as a powerful means to study biophysical/biochemical processes; many new insights are obtained from this single-molecule perspective. One phenomenon recently observed in single-molecule biophysics experiments is subdiffusion, which largely departs from the classical Brownian diffusion theory. In this talk, by introducing fractional Gaussian noise into the generalized Langevin equation, we propose a model to describe the subdiffusion. We will study the analytical properties of the model, compare the model predictions with experiments, look at its connection with reaction networks, and explore the implications of the model on enzyme reactions.