  A new mechanism for an increased event production in the large $Q^2$, $x$
region at HERA is suggested. This mechanism results from a new type of
instanton-induced quark-quark interaction, which is related to non-zero quark
modes in the instanton field. We estimate the contribution of this interaction
to the valence quark structure function $F_2^v$ using the gas instanton model
approximation for the QCD vacuum. It is shown that this interaction can give a
large contribution to $F_2^v$, especially at large values of $Q^2$. The strong
dependence of this contribution on the quark masses and $Q^2$ is discussed, and
it is concluded that a large charm quark contribution to events at high $Q^2$
can result from charm pair creation in the instanton field. We also obtain a
sizeable contribution to the valence quark longitudinal structure function
$F_L^v$ at high $Q^2$. Experimental observables which can check this instanton
mechanism in the high $Q^2$ region at HERA are suggested.
