Extended Data Fig. 4: Effect of aficamten, blebbistatin, and mavacamten on actin-activated phosphate release.
From: Aficamten is a small-molecule cardiac myosin inhibitor designed to treat hypertrophic cardiomyopathy
Bovine cardiac myosin S1 was rapidly mixed with ATP, aged, and then rapidly mixed with actin and MDCC-PBP. Final concentrations after mixing: 0.5 µM myosin, 0.25 µM ATP, 14 µM actin, 5 µM MDCC-PBP. Aficamten, blebbistatin, or mavacamten were included in all solutions at 40 µM. (A) Phosphate release rate and amplitude as a function of age time in the presence of aficamten. (B) Phosphate release rate and amplitude as a function of age time in the presence of mavacamten or blebbistatin. (C) Representative phosphate release reaction with 2 second age time. (D) Representative phosphate release reaction with 30 second age time. Data were best fit to the sum of two exponentials (3), with the exception of reactions containing mavacamten which were well fit with a single exponential (2), due to small amounts of ATP present in the actin solutions. Note that the amplitude of the fast rate of Pi release declines at longer age times under control conditions, due to loss of phosphate during the ageing period prior to mixing with actin. Data shown is the average of four to six transients from a representative experiment. (n = 5 technical replicates) Aggregated data are shown in Table S3, S4.
