Study of Catalytic Properties of Recombinant p-Lactamases TEM-1 and TEM-171 of the Molecular Class A

摘要

Homogeneous preparations of recombinant β-lactamases TEM-1 and TEM-171 of molecular class A, differing by an amino acid substitution of valine at position 84 to isoleucine (Val84Ile), was obtained. The kinetic parameters of the (3-lactamase TEM-171 were determined using a chromogenic substrate CENTA (K_(M eff) = 23 μM, K_(cat) = 102 s~(-1)). The competitive inhibition of recombinant β-lactamases TEM-1 and TEM-171 by tazobactam was ascertained. The values of the inhibition constants in the hydrolysis of the CENTA substrate amount to 0.057 and 0.047 uM for TEM-1 and TEM-171, respectively. It was shown that the Val84Ile mutation leads to a decrease of TEM-171 enzyme thermal stability by 1.5 times.