Cocommutative elements form a maximal commutative subalgebra in quantum matrices

In this paper we prove that the subalgebras of cocommutative elements in the quantized coordinate rings of $M_{n}$, $GL_{n}$ and $SL_{n}$ are the centralizers of the trace $x_{1,1}+\dots+x_{n,n}$ in each algebra, for $q\in\mathbb{C}^{\times}$ being not a root of unity. In particular, it is not only a commutative subalgebra as it was known before, but it is a maximal one.