Temperature-dependent optical rotatory dispersion properties of helical muscle proteins and homopolymers
✍ Scribed by Søren Hvidt; Michael E. Rodgers; William F. Harrington
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1985
- Tongue
- English
- Weight
- 793 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0006-3525
No coin nor oath required. For personal study only.
✦ Synopsis
Synopsis
Thermally induced helix-coil transitions of myosin rod, light meromyosin, and tropomyosin were studied by optical rotatory dispersion (ORD). Fractional helicity was calculated from both the Moffitt-Yang parameter, b,, and the corrected mean residue rotation [m'] at 231.4 nm. Between 3 and 3WC, [m'] increases linearly with a slope of 59/"C, whereas b, is virtually constant, indicating apparently different thermal melting behavior. Poly(L4ysine) and poly(~-glutamic acid) in their helical forms and myoglobin also show a nearly linear temperature dependence of [m'Iul I . Muscle proteins in 6M guanidine hydrochloride and the random-coil forms of the homopolymers exhibit temperature-dependent values of [ 7 7 ~' ] ~~, and bo-We conclude from these observations that ORD properties of both a-helices and random-coil polypeptides have significant intrinsic temperature dependencies. A new method of estimating fractional helicity as a function of temperature is proposed.