Fig. 4: HCM mutations Y115H and E497D reduce the super relaxed state fraction of human β-cardiac myosin HMM.

Representative traces showing the kinetics of mant-ATP turnover by 8 and 15-hep constructs of a WT, b Y115H, and c E497D myosin. The inset in (a) shows a schematic of two-headed short (8-hep) and long (15-hep) tailed HMM protein constructs. The data is fit to a double exponential function (solid line) and fitted fluorescence values at t = 0 and t = ∞ were used to normalize the individual curves. d, e Quantification of the single turnover data showing (d) relative amplitude of the slow rate constants (% SRX) for the 8-hep and 15-hep constructs, and the (e) fast (DRX) and slow (SRX) rate constants for 15-hep constructs (see Supplementary Table 2 for 8-hep rate constants) for all three proteins. Data is combined from 5 independent fluorescence transients from 3 biological protein preparations, mean values ± SEM are plotted. A two-sample, two-sided unequal variance t test (Welch’s t test) was used to compare WT and each mutant. n.s. indicates p > 0.05; * indicates p ≤ 0.05; ** indicates p ≤ 0.01, *** indicates p ≤ 0.001, **** indicates p ≤ 0.0001. All numbers including exact p-values from multiple pairwise comparisons shown here are given in Supplementary Table 2. Source data are provided as a Source Data file.