posted on 2021-08-20, 15:33authored byCristiano Mota, Ana Diniz, Catarina Coelho, Teresa Santos-Silva, Mariam Esmaeeli, Silke Leimkühler, Eurico J. Cabrita, Filipa Marcelo, Maria João Romão
Human aldehyde oxidase (hAOX1) is
mainly present in the liver and
has an emerging role in drug metabolism, since it accepts a wide range
of molecules as substrates and inhibitors. Herein, we employed an
integrative approach by combining NMR, X-ray crystallography, and
enzyme inhibition kinetics to understand the inhibition modes of three
hAOX1 inhibitorsthioridazine, benzamidine, and raloxifene.
These integrative data indicate that thioridazine is a noncompetitive
inhibitor, while benzamidine presents a mixed type of inhibition.
Additionally, we describe the first crystal structure of hAOX1 in
complex with raloxifene. Raloxifene binds tightly at the entrance
of the substrate tunnel, stabilizing the flexible entrance gates and
elucidating an unusual substrate-dependent mechanism of inhibition
with potential impact on drug–drug interactions. This study
can be considered as a proof-of-concept for an efficient experimental
screening of prospective substrates and inhibitors of hAOX1 relevant
in drug discovery.