Apart from their effect on the interactions, calculations of the protonisation fluctuation contribution to protein capacitance and polarizability are scarce, which is why we embark in this work upon a more detailed analysis of their properties. Specifically, based on previously introduced methodology we will investigate CR effects of the protein net charge and net dipole moment as well as the corresponding charge fluctuations, quantified by the capacitance response function, and the dipole fluctuations, quantified by the dielectric response function. Our work generalizes some aspects of the seminal approach of Kirkwood and Shumaker and takes explicitly into account the electrostatic interactions on the weak-coupling level in the calculations of the response functions.