Partition behaviour of thaumatin derivatives in poly(ethyleneglycol)/salt aqueous two-phase systems

M.V. MIRANDA; H.M. FERNÁNDEZ LAHORE; O. CASCONE

BIOSEPARATION

Kluwer Academic Publishers

Año: 1996 vol. 6 p. 315 - 321

0923-179X

In order to assess üe influence of the protein charge on its partitioning behaviour in poly(ethyleneglycol/salt aqueous two-phase systems, four thaumatin derivatives with isoelectric points around 4.0, 5.2,8.7 and 9.2 were obtained by succinylation and isolated by isoelectric focusing and chromatofocusing. The modification reaction was mild enough to preserve the tertiary structure of the proteins, as judged by circular dichroism measurements and fourth derivative UV spectra. The surface hydrophobicity of the thaumatin derivatives with pls 5.2,8.7 and 9.2 - as determined by hydrophobic interaction chromatography- was not modified by the succinylation treatment. Partition constants of the derivatives in poly(ethyleneglycol)/phosphate, citrate and sulphate aqueous two-phase systems at pHs between 7.0 and 9.5 indicate that the partition is not dependent on the protein charge in the poly(ethyleneglycol)/salt systems studied.