sentence: To a solution of fetuin41 as a donor substrate ( 25 μ L , 3 mM in 0.1 mM phosphate buffer pH 7.0 ) and triazole-linked acceptor substrates 8 – 10 and 19 ( 25 μ L , 1 mM in 0.1 mM phosphate buffer pH 7.0 ) was added TcTS enzyme ( 25 μ L ) .