The impact of the different integral scales of two isotropic turbulent fields on the dynamics of a shear-free turbulent mixing layer is investigated. To this end, two-dimensional incompressible Navier-Stokes equation is numerically solved using pseudo-spectral method. Governing equations are considered in the vorticity-stream function formulation to guarantee the divergence freeness of the velocity field. Dynamics of the turbulent interaction is examined through relevant statistical parameters such as skewness and kurtosis of the velocity components and their spatial derivatives. Moreover, the efficiency of mixing is investigated by considering the length and curvature of the mixing layer. It has been observed that increasing the difference between the initial integral length scales of two isotropic turbulent fields increases the mixing and anisotropic level of interaction.