  We apply a generalized active Brownian particles (ABP) model to derive
diffusion coefficient of a stochastic nanoswimmer subject to an external force.
We assume the underlying self-propulsion mechanism is based upon chemical
reactions. We show that diffusion coefficient grows quadratically with the
amplitude of the force regardless of its directions. The effect is a direct
consequence of the fundamental principle of microscopic reversibility imposed
upon the mechanism of self-propulsion and as such is universal. This result may
shed new light on the interpretation of the experiments on enhanced diffusion
of enzymes in the presence of their substrates, and provide a straightforward
way towards experimental verification of the used model and its basic
assumptions.
