PMC:2812710 / 3991-5507 JSONTXT

{"project":"MyTest","denotations":[{"id":"19159925-10692345-28773038","span":{"begin":293,"end":297},"obj":"10692345"},{"id":"19159925-12844240-28773039","span":{"begin":1343,"end":1347},"obj":"12844240"}],"namespaces":[{"prefix":"_base","uri":"https://www.uniprot.org/uniprot/testbase"},{"prefix":"UniProtKB","uri":"https://www.uniprot.org/uniprot/"},{"prefix":"uniprot","uri":"https://www.uniprot.org/uniprotkb/"}],"text":"Sedimentation velocity experiments were performed on a Beckman XLI analytical ultracentrifuge at a rotor speed of 55,000 rpm and at 20°C in Al-double-sector cells of optical path 12 mm using interference optics. The evaluation program Sedfit for continuous particle size distributions (Schuck 2000) was used for data analysis. The regularization method used was the Tikhonov-Philips 2nd derivative, and the confidence level (F ratio) chosen was 0.8–0.9. By fitting for (f/f sph) in a nonlinear regression, an estimate of the weight-average frictional ratio of all macromolecules in solution is obtained, where f is the frictional ratio of the solute macromolecule and f sph is the frictional ratio of the rigid sphere with the same “anhydrous” volume (free of solvent) as the macromolecule. The final result is the differential distribution (dc(s)/ds) of the sample, which is named c(s). It is scaled such that the area under the c(s) curve between the smallest s value, s 1, and the largest one, s 2, in the distribution will give the loading concentration of macromolecules between these sedimentation coefficients (expressed in number of fringes, J, in the case of interference optics). J, which is proportional to the polymer concentration in solution, was used to calculate the refractive index increment: (Δn/Δc) = Jλ/Kcl (Pavlov et al. 2003), where λ is the wavelength (675 nm), K the magnifying coefficient and l the optical path. With K = 1 and l = 12 mm we obtain: Δn/Δc = 5.625 × 10−5(J/c) and c in g/cm3."}

{"project":"2_test","denotations":[{"id":"19159925-10692345-28773038","span":{"begin":293,"end":297},"obj":"10692345"},{"id":"19159925-12844240-28773039","span":{"begin":1343,"end":1347},"obj":"12844240"}],"text":"Sedimentation velocity experiments were performed on a Beckman XLI analytical ultracentrifuge at a rotor speed of 55,000 rpm and at 20°C in Al-double-sector cells of optical path 12 mm using interference optics. The evaluation program Sedfit for continuous particle size distributions (Schuck 2000) was used for data analysis. The regularization method used was the Tikhonov-Philips 2nd derivative, and the confidence level (F ratio) chosen was 0.8–0.9. By fitting for (f/f sph) in a nonlinear regression, an estimate of the weight-average frictional ratio of all macromolecules in solution is obtained, where f is the frictional ratio of the solute macromolecule and f sph is the frictional ratio of the rigid sphere with the same “anhydrous” volume (free of solvent) as the macromolecule. The final result is the differential distribution (dc(s)/ds) of the sample, which is named c(s). It is scaled such that the area under the c(s) curve between the smallest s value, s 1, and the largest one, s 2, in the distribution will give the loading concentration of macromolecules between these sedimentation coefficients (expressed in number of fringes, J, in the case of interference optics). J, which is proportional to the polymer concentration in solution, was used to calculate the refractive index increment: (Δn/Δc) = Jλ/Kcl (Pavlov et al. 2003), where λ is the wavelength (675 nm), K the magnifying coefficient and l the optical path. With K = 1 and l = 12 mm we obtain: Δn/Δc = 5.625 × 10−5(J/c) and c in g/cm3."}