  We study numerically a disordered version of the model for DNA denaturation
transition (DSAW-DNA) consisting of two interacting SAWs in 3d, which undergoes
a first order transition in the homogeneous case. The two possible values eAT
and eGC of the interactions between base pairs are taken as quenched random
variables distributed with equal probability along the chain. We measure
quantities averaged over disorder such as the energy density, the specific heat
and the probability distribution of the loop lengths. When applying the scaling
laws used in the homogeneous case we find that the transition seems to be
smoother in presence of disorder, in agreement with general theoretical
arguments. Nevertheless we can not rule out the possibility of a still first
order transition.
