Effect of chain length and concentration of anionic surfactants on the conformational transitions of poly(L-ornithine) and poly(L-lysine) in aqueous solution

The conformation of poly(L-ornithine) (PLO) and poly(L-lysine) (PLL) in solutions of sodium alkyl sulfates, CH₃(CH₂)_nSO₄Na with n = 7, 9, 11, 13 and 15 was studied by circular dichroism. PLO adopts a helical conformation in all 5 homologs and PLL a β-form in only 4 of the homologs. With octyl sulfate PLL has a helical conformation instead. These conformations were observed in solution of surfactants both below and above the critical micelle concentration.     

Gas-liquid chromatographic analysis of cyasin in cycad flour

A method for the quantitative determination of cycasin from cycad flour by gas-liquid chromatography is described. The flour is extracted with 70% ethanol and the residue from the dried extract is directly trimethylsilylated. Androsterone was found to be an excellent internal standard. The average content of cycasin from ten separate analyses of one lot of flour was $\text{0.429 gm}\text{100 gm}$. The method is rapid, sensitive, and not hindered by contaminating compounds.     

Second virial coefficient of alpha-crystallin

Light scattering studies were performed on bovine alpha-crystallin measuring the scattering intensities as a function of scattering angle, concentration, and temperature. The data yielded the molecular weight, radius of gyration, and second virial coefficient of alpha-crystallin at different temperatures. The second virial coefficient increased with increasing temperature. Both the enthalpy and entropy of solution of alpha-crystallin are positive. The Flory theta temperature was found to be 271 K.