  Here we investigate the connection of broad emission line shapes and
continuum light curve variability time scales of type-1 Active Galactic Nuclei
(AGN). We developed a new model to describe optical broad emission lines as an
accretion disk model of a line profile with additional ring emission. We
connect ring radii with orbital time scales derived from optical light curves,
and using Kepler's third law, we calculate mass of central supermassive black
hole (SMBH). The obtained results for central black hole masses are in a good
agreement with {other methods. This indicates that the variability time scales
of AGN may not be stochastic, but rather connected to the orbital time scales
which depend on the central SMBH mass.
