The constraint on FCNC coupling of the top quark with a gluon from ep-collisions

Using the constraint on the single top production cross-section obtained at the HERA collider, σ(ep→etX), we evaluate an upper limit on coupling constant of the anomalous top quark interaction with a gluon via flavor-changing neutral current: |κtgq/Λ|≲0.4TeV−1, BR(t→gq)<13%.