  We study infrared contributions to the QCD description of the HERA data on
the structure function $F_{2}$ within the \textit{generalized} DAS
approximation. We argue that this approximation is a natural one and consistent
with the phenomenon of dynamical mass generation in QCD. The investigation is
performed at next-to-leading order by using the leading-twist expansion of
$F_{2}(x,Q^{2})$ and by adopting an effective charge whose finite infrared
behavior is constrained by a dynamical gluon mass. We propose one ansatz for
the behavior of this effective coupling beyond leading order. The dependence of
the experimental data on the infrared value of the effective charge is used in
order to study the asymptotic behavior of the running gluon mass. The deep
inelastic structure function $F_{2}$ obtained in this approach shows very good
agreement with the experimental data.
