Method for operating a brake system, and brake system

A brake system for a vehicle, comprising:

• an actuating circuit having a positioner system actuable by an actuation device for generation of a brake request signal;
• an active circuit having a pressure generation device, at least one wheel brake hydraulically coupled with the pressure generation device, and an isolation valve, which is situated in a hydraulic path between the pressure generation device and the wheel brake, a preloading device preloading the isolation valve to a closed state counter to an inflow direction of a volume flow into a brake-side section of the hydraulic path between the isolation valve and the wheel brake;
• and
• a control unit which is connected to the positioner device of the actuating circuit, to the pressure generation device, and to the isolation valve, the control unit being configured to ascertain from the brake request signal a setpoint brake pressure required in the active circuit, to actuate the pressure generation device for the adjustment of an actual brake pressure in the active circuit according to the setpoint brake pressure, to close the isolation valve for the hydraulic decoupling of the wheel brake from the pressure generation device, and to open the isolation valve for the hydraulic coupling of the wheel brake in that the control unit actuates the pressure generation device for adjustment of the actual brake pressure in a pressure-generator-side section of the hydraulic path between the isolation valve and the pressure generation device according to the setpoint brake pressure, and simultaneously applies an opening force to the isolation valve such that a compensation of a closing force by which the preloading device preloads the isolation valve takes place.