  Some ingredients of the BRST construction for quantum Lie algebras are
applied to a wider class of quadratic algebras of constraints. We build the
BRST charge for a quantum Lie algebra with three generators and
ghost-anti-ghosts commuting with constraints. We consider a one-parametric
family of quadratic algebras with three generators and show that the BRST
charge acquires the conventional form after a redefinition of ghosts. The
modified ghosts form a quadratic algebra. The family possesses a non-linear
involution, which implies the existence of two independent BRST charges for
each algebra in the family. These BRST charges anticommute and form a double
BRST complex.
