  Here we investigate the H$\beta$ and Mg II spectral line parameters used for
the black hole mass (M$_{\rm BH}$) estimation for a sample of Type 1 Active
Galactic Nuclei (AGN) spectra selected from the Sloan Digital Sky Survey (SDSS)
database. We have analyzed and compared the virialization of the H$\beta$ and
Mg II emission lines, and found that the H$\beta$ line is more confident virial
estimator than Mg II. We have investigated the influence of the Balmer
continuum emission to the M$_{\rm BH}$ estimation from the UV parameters, and
found that the Balmer continuum emission can contribute to the overestimation
of the M$_{\rm BH}$ on average for ~ 5% (up to 10%).
