Scientia Sinica

TSAO, TAN, & PENG: TROPOMYOSINS FROM DIFFERENT SOURCES 103

Fig. 12. Viscosity of sepia tropomyosin. 31°C, solvent same as in Fig. 6.

The values for the intrinsic viscosity [7] were obtained by graphical ex[7] x 100 v each value of [7] by employing the partial specific volume 7=0.71™!, and the bydration value 0.25 g/g! for rabbit tropomyosin. The axial ratio a/b was evaluated with the help of Simha’s equation and the results are given in Table 3. Owing to the high asymmetry of tropomyosin, slight variations in the values for # and hydration do not affect the order of magnitude of the

calculated axial ratios.

trapolation. The viscosity increment » = was calculated for

Table 3, Shape of Tropomyosins from Viscometric Data. a EE

Sclvent a/b Tropomyosin ————_ [7] YY =< oa aa Note 25% HypH I | Anhydrous Waraton Rabbit striated muscle 2, 0.3 0.52 74 30 25 (30) 6.5 Le 0.57 80 31 26 (30) Duck gizzard smooth muscle 2 0.2 | 0.65 | 92 34 29 7.0 0.6 | 0.65 92 34 29 Prawn striated muscle alt 0.1 | 0.77 | 109 38 32 7.0 1.6 0.35 49 23 19 Sepia mantle smooth muscle 7.0 16: |/(0534 ||) 48 23 19 Pig cardiac muscle 7.0 1.6 | 0.45 63 27 22

By comparing Tables 2 and 3, it is seen that for rabbit and prawn tropomyosins the. axial ratios from the osmotic and viscometric data agree well with each other; whereas for the other tropomyosins Zimm and Onsager’s