  We study polarized-spin structure functions of the nucleon within the
bosonized Nambu-Jona-Lasinio model where the nucleon emerges as a chiral
soliton. We present the electromagnetic polarized structure functions,
$g_{1}(x)$ and $g_{2}(x)$ for $ep$ scattering and discuss various sum rules in
the valence quark approximation. This approximation is justified because in
this model axial properties of the nucleon are dominated by their valence quark
contributions. We find that these structure functions are well localized in the
interval $0\le x \le1$. We compare the model predictions on the polarized
structure functions with data from the E143 experiment by evolving them from
the scale characteristic of the NJL-model to the scale of the data.
Additionally a comparison is made with parameterized data at a momentum scale
commensurate with the model calculation.
