Midazolam as a Probe for Drug-Drug Interactions Mediated by CYP3A4: Homotropic Allosteric Mechanism of Site-Specific Hydroxylation.

ABSTRACT: We developed an efficient and sensitive probe for drug-drug interactions mediated by human CYP3A4 by using midazolam (MDZ) as a probe substrate. Using global analysis of four parameters over several experimental data sets, we demonstrate that the first MDZ molecule (MDZ1) binds with high affinity at the productive site near the heme iron and gives only hydroxylation at the 1 position (1OH). The second midazolam molecule (MDZ2) binds at an allosteric site at the membrane surface and perturbs the position and mobility of MDZ1 such that the minor hydroxylation product at the 4 position (4OH) is formed in a 1:2 ratio (35%). No increase in catalytic rate is observed after the second MDZ binding. Hence, the site of the 1OH:4OH metabolism ratio is a sensitive probe for drugs, such as progesterone

SUBMITTER: Denisov IG 

PROVIDER: S-EPMC8857940 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature