Table 1.

Local and global flexibility of tropomyosin. Flexibility determined from MD simulations of either isolated tropomyosin molecules or tropomyosin when bound to F-actin [5,8,13]. (D175N was not studied on F-actin, since MD runs of actin-tropomyosin are extremely expensive.) δ measures true flexibility as the mean deviation angle (see Fig. S1) from the time-averaged position between the two ends of a given segment of the rod [5,8,13].

Tropomyosin examined	δ - F-actin-free tropomyosin (°)	δ - Tropomyosin bound to F-actin (°)
Wild-type
Local δ - at residue 175	4.45 ± 0.05	3.59 ± 0.19
Local δ - at residue 180	4.21 ± 0.05	3.60 ± 0.21
δ over entire tropomyosin	22.0 ± 1.9	9.89 ± 0.11
D175N
Local δ - at residue 175	4.39 ± 0.02	--
Local δ - at residue 180	5.86 ± 0.08*	--
δ over entire tropomyosin	30.5 ± 0.19*	--
E180G
Local δ - at residue 175	4.47 ± 0.09	3.85 ± 0.01
Local δ - at residue 180	5.30 ± 0.08*	4.94 ± 0.30*
δ over entire tropomyosin	27.6 ± 1.3*	10.9 ± 0.50*

Local δ: segment is taken over 9 residues centered at either residue 175 or 180. δ over entire tropomyosin: segment is the whole tropomyosin.

^*p<0.01 compared to wild-type; error of corresponding half-data sets reported.