Table 1.
Comparison among native fibers, and four forms of actin reconstituted fibers
| Parameter (unit) | Native fiber | BVC actin | WT actin | A331P actin | Insect actin |
|---|---|---|---|---|---|
| Ta (T0) | N/A | 0.73±0.07 (12) | 0.75±0.06 (11) | 0.55±0.03*§ (13) | 0.52±0.05*§ (6) |
| THC (T0) | N/A | 0.98±0.04 (12) | 0.85±0.06 (11) | 0.65±0.02*§ (13) | 0.39±0.05*§ (6) |
| TLC (T0) | 0.06±0.01 (10) | 0.08±0.02 (12) | 0.08±0.01 (11) | 0.05±0.01*§ (13) | 0.07±0.02 (6) |
| Tact (T0) | 0.94±0.01 (10) | 0.91±0.02 (12) | 0.76±0.06 (11) | 0.61±0.03*#§ (13) | 0.31±0.06 *#§ (6) |
| Rigor Stiffness (MPa) | 2.12±0.15 (10) | 2.23±0.21 (12) | 2.24±0.17 (11) | 0.92±0.09*#§ (13) | 1.62±0.46 (5) |
| YHC (MPa) | 0.94±0.08 (10) | 0.92±0.10 (12) | 0.82±0.12 (11) | 0.44±0.04*#§ (13) | 0.62±0.12 (5) |
| YLC (MPa) | 0.19±0.03 (10) | 0.30±0.05 (12) | 0.24±0.05 (11) | 0.14±0.01*§ (13) | 0.20±0.04 (5) |
| Yact (MPa) | 0.73±0.06 (10) | 0.62±0.08 (12) | 0.59±0.08 (11) | 0.30±0.03*#§ (13) | 0.42±0.15 (5) |
| pCa50 | 5.69±0.01(10) | 5.68±0.02 (12) | 5.69±0.02 (11) | 5.57±0.03*#§ (13) | 5.53±0.02*#§ (4) |
| Hill Factor (Cooperativity) | 3.22±0.18 (10) | 2.71±0.23 (12) | 2.6±0.3 (11) | 2.33±0.34# (13) | 2.62±0.19# (4) |
| K0 (mM−1) | 17.7±1.3 (9) | 69.6±8.3# (6) | 35.04±6.3#§ (6) | 31.0±5.44#§ (7) | 84.4 (1) |
| K1 (mM−1) | 1.26±0.29 (8) | 2.10±0.44# (8) | 2.07±0.28# (10) | 1.64±0.18 (7) | 2.77±0.96 (4) |
| K2 | 0.88±0.13 (8) | 1.00±0.15 (8) | 0.78±0.13 (10) | 0.69±0.10 (7) | 0.40±0.06*#§ (4) |
| K4 | 0.70±0.08 (7) | 0.68±0.16 (7) | 0.76±0.14 (8) | 0.92±0.16 (7) | 1.92±0.15*#§ (4) |
| K5 (mM−1) | 0.26±0.04 (7) | 0.19±0.05 (7) | 0.22±0.04 (8) | 0.17±0.04 (7) | 1.06±0.34*#§ (4) |
| k2 (s−1) | 14.46±2.16 (8) | 21.3±3.0*# (8) | 11.99±1.42§ (10) | 8.44±1.65§ (7) | 4.99±0.59*#§ (4) |
| k−2 (s−1) | 16.83±2.28 (8) | 19.8±2.1 (8) | 16.83±1.53 (10) | 12.24±1.34 (7) | 13.0±1.7 (4) |
| k4 (s−1) | 6.75±0.79 (7) | 7.45±0.97 (7) | 7.75±0.75 (8) | 13.19±1.73*#§ (7) | 12.1±1.9*#§ (4) |
| k−4 (s−1) | 9.29±0.70 (7) | 12.29±1.89 (7) | 11.94±1.94 (8) | 15.84±2.44# (7) | 6.21±0.7*#§ (4) |
Notes. WT actin and A331P actin are recombinant proteins produced by baculovirus infected insect cells. T0: Tension of original bovine cardiac muscle fibers at the standard activating conditions (5S8P) at pCa 4.66. T0=26.85±1.13 KPa (n=41). Only the first row (Ta) was measured in the absence of Tm/Tn, whereas others were measured after reconstitution with Tm/Tn. Ta: Tension of the actin filament reconstituted fibers at the standard activating conditions (5S8P). THC: Tension at pCa 4.66. TLC: Tension at pCa 8. All experiments were performed at 25°C. All the data are shown as mean ± S. E. M.
Significantly different from WT actin (p<0.05);
Significantly different from native fibers (p<0.05);
Significantly different from BVC actin reconstituted fibers (p<0.05).